HI ALL,
Suppose i did not use identity for generating sequence in a
table.Also there is no sequence no column or no primary key on a
column. Then how to find last record in a table. Suppose there are 10
rows. How can i fetch 10th rows record.
Define your SQL SELECT statement , and THEN use ORDER BY myCol DESC -
select TOP 1. That's assuming there are 10 records.
If there are more than 10 records , and you are using SQL 2005 , you could
do something like:
SELECT col1, col2, ROW_NUMBER() OVER (ORDER BY Col2 DESC)AS RowFROm
myTableWHERE Row = 10
Jack Vamvas
___________________________________
Search IT jobs from multiple sources- http://www.ITjobfeed.com
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> HI ALL,
> Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.
|||On Jan 16, 2:50Xpm, "MC" <markoDOTculo@.gmailDOTcom> wrote:
> First you need to define 10th. What does it mean exactly? Last fetched, last
> by some value, last..... Without primary key you basically dont have a
> consistent approach, so some kind of definition is definitely needed here.
> MC
> "mohit" <goenka.mo...@.gmail.com> wrote in message
> news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
>
>
> - Show quoted text -
HI,
10th means last record. Without primary key there is no consitent
approach but suppose we dont have then how we will find.
|||MC
SELECT TOP 1 col FROM tbl ORDER BY whatever DESC
"MC" <markoDOTculo@.gmailDOTcom> wrote in message
news:5C08A997-8EFD-4C5B-96FD-AC49EFC9DFB6@.microsoft.com...
> First you need to define 10th. What does it mean exactly? Last fetched,
> last by some value, last..... Without primary key you basically dont have
> a consistent approach, so some kind of definition is definitely needed
> here.
>
> MC
>
> "mohit" <goenka.mohit@.gmail.com> wrote in message
> news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
>
|||On Jan 16, 3:22Xpm, mohit <goenka.mo...@.gmail.com> wrote:
> HI ALL,
> X X X Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.
In a set there is no such thing as last record.
|||On Jan 16, 3:22Xpm, "Uri Dimant" <u...@.iscar.co.il> wrote:
> MC
> SELECT TOP 1 col FROM tbl ORDER BY whatever DESC
> "MC" <markoDOTculo@.gmailDOTcom> wrote in message
> news:5C08A997-8EFD-4C5B-96FD-AC49EFC9DFB6@.microsoft.com...
>
>
>
> - Show quoted text -
Hi,
Sorry yaar but its not working. When we do order by col_name desc
the rows gets shuffle due to which answer is coming wrong
|||On Jan 16, 3:28Xpm, SB <othell...@.yahoo.com> wrote:
> On Jan 16, 3:22Xpm, mohit <goenka.mo...@.gmail.com> wrote:
>
> In a set there is no such thing as last record.
Can you tell what set means. i am asking from table how to fetch last
record i.e last row from a table
|||On Jan 16, 4:45Xpm, mohit <goenka.mo...@.gmail.com> wrote:
> On Jan 16, 3:28Xpm, SB <othell...@.yahoo.com> wrote:
>
>
> Can you tell what set means. i am asking from table how to fetch last
> record i.e last row from a table
A table consists of a set of records. It is not a sequence so that you
have first or last record. A set is an unordered set of records.
|||> Sorry yaar but its not working. When we do order by col_name desc
> the rows gets shuffle due to which answer is coming wrong
How do you know it is not working if there is no data in the row to identify
the order of insertion?
An important relational database concept is that a table is an unordered set
of rows. Rows may be returned in an arbitrary sequence unless you specify
ORDER BY. If you want data returned in the sequence in which rows were
inserted, you'll need an incrementing column like inserted datetime or
identity for the ordering.
Hope this helps.
Dan Guzman
SQL Server MVP
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:d4d2d6c5-c6e0-4612-9f57-13accf2ff8b1@.i7g2000prf.googlegroups.com...
On Jan 16, 3:22 pm, "Uri Dimant" <u...@.iscar.co.il> wrote:
> MC
> SELECT TOP 1 col FROM tbl ORDER BY whatever DESC
> "MC" <markoDOTculo@.gmailDOTcom> wrote in message
> news:5C08A997-8EFD-4C5B-96FD-AC49EFC9DFB6@.microsoft.com...
>
>
>
> - Show quoted text -
Hi,
Sorry yaar but its not working. When we do order by col_name desc
the rows gets shuffle due to which answer is coming wrong
|||"mohit" <goenka.mohit@.gmail.com> wrote in message
news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> HI ALL,
> Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.
As others have said, w/o a primary key, there's no such thing as a "last
record" defined.
And in fact, without an ORDER BY you can never guarantee the order you'll
return the data in.
SELECT * from FOO may in fact return a different order of results at
different times.
This could be due to what's in the memory cache at the time, if the engine
decides to parallize the query across different CPUs, etc.
Now, MOST LIKELY for 10 rows, a simple "select * from FOO" will return the
data in the order it was inserted but that's absolutely no guarantee this is
true.
You may want to google the definition of a "SET" or "TABLE" within SQL.
They have no inherent order.
So sorry to say, you probably can't get the answer to the question you seek
(at least not the way it's posed.)
Greg Moore
SQL Server DBA Consulting Remote and Onsite available!
Email: sql (at) greenms.com http://www.greenms.com/sqlserver.html
sql
Showing posts with label identity. Show all posts
Showing posts with label identity. Show all posts
Monday, March 26, 2012
Fetch last record in a table
HI ALL,
Suppose i did not use identity for generating sequence in a
table.Also there is no sequence no column or no primary key on a
column. Then how to find last record in a table. Suppose there are 10
rows. How can i fetch 10th rows record.First you need to define 10th. What does it mean exactly? Last fetched, last
by some value, last..... Without primary key you basically dont have a
consistent approach, so some kind of definition is definitely needed here.
MC
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> HI ALL,
> Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.|||Define your SQL SELECT statement , and THEN use ORDER BY myCol DESC -
select TOP 1. That's assuming there are 10 records.
If there are more than 10 records , and you are using SQL 2005 , you could
do something like:
SELECT col1, col2, ROW_NUMBER() OVER (ORDER BY Col2 DESC)AS RowFROm
myTableWHERE Row = 10
Jack Vamvas
___________________________________
Search IT jobs from multiple sources- http://www.ITjobfeed.com
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> HI ALL,
> Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.|||On Jan 16, 2:50=A0pm, "MC" <markoDOTculo@.gmailDOTcom> wrote:
> First you need to define 10th. What does it mean exactly? Last fetched, la=st
> by some value, last..... Without primary key you basically dont have a
> consistent approach, so some kind of definition is definitely needed here.=
> MC
> "mohit" <goenka.mo...@.gmail.com> wrote in message
> news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
>
> > HI ALL,
> > =A0 =A0 =A0Suppose i did not use identity for generating sequence in a
> > table.Also there is no sequence no column or no primary key on a
> > column. Then how to find last record in a table. Suppose there are 10
> > rows. How can i fetch 10th rows record.- Hide quoted text -
> - Show quoted text -
HI,
10th means last record. Without primary key there is no consitent
approach but suppose we dont have then how we will find.|||MC
SELECT TOP 1 col FROM tbl ORDER BY whatever DESC
"MC" <markoDOTculo@.gmailDOTcom> wrote in message
news:5C08A997-8EFD-4C5B-96FD-AC49EFC9DFB6@.microsoft.com...
> First you need to define 10th. What does it mean exactly? Last fetched,
> last by some value, last..... Without primary key you basically dont have
> a consistent approach, so some kind of definition is definitely needed
> here.
>
> MC
>
> "mohit" <goenka.mohit@.gmail.com> wrote in message
> news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
>> HI ALL,
>> Suppose i did not use identity for generating sequence in a
>> table.Also there is no sequence no column or no primary key on a
>> column. Then how to find last record in a table. Suppose there are 10
>> rows. How can i fetch 10th rows record.
>|||On Jan 16, 3:22=A0pm, mohit <goenka.mo...@.gmail.com> wrote:
> HI ALL,
> =A0 =A0 =A0 Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.
In a set there is no such thing as last record.|||On Jan 16, 3:22=A0pm, "Uri Dimant" <u...@.iscar.co.il> wrote:
> MC
> SELECT TOP 1 col FROM tbl ORDER BY whatever DESC
> "MC" <markoDOTculo@.gmailDOTcom> wrote in message
> news:5C08A997-8EFD-4C5B-96FD-AC49EFC9DFB6@.microsoft.com...
>
> > First you need to define 10th. What does it mean exactly? Last fetched,
> > last by some value, last..... Without primary key you basically dont ha=ve
> > a consistent approach, so some kind of definition is definitely needed
> > here.
> > MC
> > "mohit" <goenka.mo...@.gmail.com> wrote in message
> >news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> >> HI ALL,
> >> =A0 =A0 =A0Suppose i did not use identity for generating sequence in a
> >> table.Also there is no sequence no column or no primary key on a
> >> column. Then how to find last record in a table. Suppose there are 10
> >> rows. How can i fetch 10th rows record.- Hide quoted text -
> - Show quoted text -
Hi,
Sorry yaar but its not working. When we do order by col_name desc
the rows gets shuffle due to which answer is coming wrong|||On Jan 16, 3:28=A0pm, SB <othell...@.yahoo.com> wrote:
> On Jan 16, 3:22=A0pm, mohit <goenka.mo...@.gmail.com> wrote:
> > HI ALL,
> > =A0 =A0 =A0 Suppose i did not use identity for generating sequence in a
> > table.Also there is no sequence no column or no primary key on a
> > column. Then how to find last record in a table. Suppose there are 10
> > rows. How can i fetch 10th rows record.
> In a set there is no such thing as last record.
Can you tell what set means. i am asking from table how to fetch last
record i.e last row from a table|||On Jan 16, 4:45=A0pm, mohit <goenka.mo...@.gmail.com> wrote:
> On Jan 16, 3:28=A0pm, SB <othell...@.yahoo.com> wrote:
> > On Jan 16, 3:22=A0pm, mohit <goenka.mo...@.gmail.com> wrote:
> > > HI ALL,
> > > =A0 =A0 =A0 Suppose i did not use identity for generating sequence in =a
> > > table.Also there is no sequence no column or no primary key on a
> > > column. Then how to find last record in a table. Suppose there are 10
> > > rows. How can i fetch 10th rows record.
> > In a set there is no such thing as last record.
> Can you tell what set means. i am asking from table how to fetch last
> record i.e last row from a table
A table consists of a set of records. It is not a sequence so that you
have first or last record. A set is an unordered set of records.|||If the 'last' you mean last added then you need a column which will define
sequence of insertions. Something like 'DateAdded' or something like that.
Otherwise, you need to specify how do YOU know which record is 'last' when
you open sample data from table.
MC
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:a53c73e5-4685-4d12-8f94-5e8a1b94b5b8@.f10g2000hsf.googlegroups.com...
On Jan 16, 2:50 pm, "MC" <markoDOTculo@.gmailDOTcom> wrote:
> First you need to define 10th. What does it mean exactly? Last fetched,
> last
> by some value, last..... Without primary key you basically dont have a
> consistent approach, so some kind of definition is definitely needed here.
> MC
> "mohit" <goenka.mo...@.gmail.com> wrote in message
> news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
>
> > HI ALL,
> > Suppose i did not use identity for generating sequence in a
> > table.Also there is no sequence no column or no primary key on a
> > column. Then how to find last record in a table. Suppose there are 10
> > rows. How can i fetch 10th rows record.- Hide quoted text -
> - Show quoted text -
HI,
10th means last record. Without primary key there is no consitent
approach but suppose we dont have then how we will find.|||> Sorry yaar but its not working. When we do order by col_name desc
> the rows gets shuffle due to which answer is coming wrong
How do you know it is not working if there is no data in the row to identify
the order of insertion?
An important relational database concept is that a table is an unordered set
of rows. Rows may be returned in an arbitrary sequence unless you specify
ORDER BY. If you want data returned in the sequence in which rows were
inserted, you'll need an incrementing column like inserted datetime or
identity for the ordering.
--
Hope this helps.
Dan Guzman
SQL Server MVP
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:d4d2d6c5-c6e0-4612-9f57-13accf2ff8b1@.i7g2000prf.googlegroups.com...
On Jan 16, 3:22 pm, "Uri Dimant" <u...@.iscar.co.il> wrote:
> MC
> SELECT TOP 1 col FROM tbl ORDER BY whatever DESC
> "MC" <markoDOTculo@.gmailDOTcom> wrote in message
> news:5C08A997-8EFD-4C5B-96FD-AC49EFC9DFB6@.microsoft.com...
>
> > First you need to define 10th. What does it mean exactly? Last fetched,
> > last by some value, last..... Without primary key you basically dont
> > have
> > a consistent approach, so some kind of definition is definitely needed
> > here.
> > MC
> > "mohit" <goenka.mo...@.gmail.com> wrote in message
> >news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> >> HI ALL,
> >> Suppose i did not use identity for generating sequence in a
> >> table.Also there is no sequence no column or no primary key on a
> >> column. Then how to find last record in a table. Suppose there are 10
> >> rows. How can i fetch 10th rows record.- Hide quoted text -
> - Show quoted text -
Hi,
Sorry yaar but its not working. When we do order by col_name desc
the rows gets shuffle due to which answer is coming wrong|||"mohit" <goenka.mohit@.gmail.com> wrote in message
news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> HI ALL,
> Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.
As others have said, w/o a primary key, there's no such thing as a "last
record" defined.
And in fact, without an ORDER BY you can never guarantee the order you'll
return the data in.
SELECT * from FOO may in fact return a different order of results at
different times.
This could be due to what's in the memory cache at the time, if the engine
decides to parallize the query across different CPUs, etc.
Now, MOST LIKELY for 10 rows, a simple "select * from FOO" will return the
data in the order it was inserted but that's absolutely no guarantee this is
true.
You may want to google the definition of a "SET" or "TABLE" within SQL.
They have no inherent order.
So sorry to say, you probably can't get the answer to the question you seek
(at least not the way it's posed.)
Greg Moore
SQL Server DBA Consulting Remote and Onsite available!
Email: sql (at) greenms.com http://www.greenms.com/sqlserver.html|||>>
10th means last record. Without primary key there is no consitent
approach but suppose we dont have then how we will find.
If you don't have a column that can tell you what "last" means, then you
could return ANY row and how would you know it wasn't the "last" row?
In SQL Server, a table is an unordered set of rows by definition. If you
say SELECT TOP 1 columns FROM table or SELECT TOP 10 columns FROM table and
you don't include an ORDER BY clause, the optimizer is free to return
whichever rows it wants... and it can change its mind when you run the query
again 5 minutes later, giving you a different set. So, if you want to
identify your "last" row, you will need to have a column that you can use to
tell SQL Server "use this column to determine last."
A
Suppose i did not use identity for generating sequence in a
table.Also there is no sequence no column or no primary key on a
column. Then how to find last record in a table. Suppose there are 10
rows. How can i fetch 10th rows record.First you need to define 10th. What does it mean exactly? Last fetched, last
by some value, last..... Without primary key you basically dont have a
consistent approach, so some kind of definition is definitely needed here.
MC
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> HI ALL,
> Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.|||Define your SQL SELECT statement , and THEN use ORDER BY myCol DESC -
select TOP 1. That's assuming there are 10 records.
If there are more than 10 records , and you are using SQL 2005 , you could
do something like:
SELECT col1, col2, ROW_NUMBER() OVER (ORDER BY Col2 DESC)AS RowFROm
myTableWHERE Row = 10
Jack Vamvas
___________________________________
Search IT jobs from multiple sources- http://www.ITjobfeed.com
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> HI ALL,
> Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.|||On Jan 16, 2:50=A0pm, "MC" <markoDOTculo@.gmailDOTcom> wrote:
> First you need to define 10th. What does it mean exactly? Last fetched, la=st
> by some value, last..... Without primary key you basically dont have a
> consistent approach, so some kind of definition is definitely needed here.=
> MC
> "mohit" <goenka.mo...@.gmail.com> wrote in message
> news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
>
> > HI ALL,
> > =A0 =A0 =A0Suppose i did not use identity for generating sequence in a
> > table.Also there is no sequence no column or no primary key on a
> > column. Then how to find last record in a table. Suppose there are 10
> > rows. How can i fetch 10th rows record.- Hide quoted text -
> - Show quoted text -
HI,
10th means last record. Without primary key there is no consitent
approach but suppose we dont have then how we will find.|||MC
SELECT TOP 1 col FROM tbl ORDER BY whatever DESC
"MC" <markoDOTculo@.gmailDOTcom> wrote in message
news:5C08A997-8EFD-4C5B-96FD-AC49EFC9DFB6@.microsoft.com...
> First you need to define 10th. What does it mean exactly? Last fetched,
> last by some value, last..... Without primary key you basically dont have
> a consistent approach, so some kind of definition is definitely needed
> here.
>
> MC
>
> "mohit" <goenka.mohit@.gmail.com> wrote in message
> news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
>> HI ALL,
>> Suppose i did not use identity for generating sequence in a
>> table.Also there is no sequence no column or no primary key on a
>> column. Then how to find last record in a table. Suppose there are 10
>> rows. How can i fetch 10th rows record.
>|||On Jan 16, 3:22=A0pm, mohit <goenka.mo...@.gmail.com> wrote:
> HI ALL,
> =A0 =A0 =A0 Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.
In a set there is no such thing as last record.|||On Jan 16, 3:22=A0pm, "Uri Dimant" <u...@.iscar.co.il> wrote:
> MC
> SELECT TOP 1 col FROM tbl ORDER BY whatever DESC
> "MC" <markoDOTculo@.gmailDOTcom> wrote in message
> news:5C08A997-8EFD-4C5B-96FD-AC49EFC9DFB6@.microsoft.com...
>
> > First you need to define 10th. What does it mean exactly? Last fetched,
> > last by some value, last..... Without primary key you basically dont ha=ve
> > a consistent approach, so some kind of definition is definitely needed
> > here.
> > MC
> > "mohit" <goenka.mo...@.gmail.com> wrote in message
> >news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> >> HI ALL,
> >> =A0 =A0 =A0Suppose i did not use identity for generating sequence in a
> >> table.Also there is no sequence no column or no primary key on a
> >> column. Then how to find last record in a table. Suppose there are 10
> >> rows. How can i fetch 10th rows record.- Hide quoted text -
> - Show quoted text -
Hi,
Sorry yaar but its not working. When we do order by col_name desc
the rows gets shuffle due to which answer is coming wrong|||On Jan 16, 3:28=A0pm, SB <othell...@.yahoo.com> wrote:
> On Jan 16, 3:22=A0pm, mohit <goenka.mo...@.gmail.com> wrote:
> > HI ALL,
> > =A0 =A0 =A0 Suppose i did not use identity for generating sequence in a
> > table.Also there is no sequence no column or no primary key on a
> > column. Then how to find last record in a table. Suppose there are 10
> > rows. How can i fetch 10th rows record.
> In a set there is no such thing as last record.
Can you tell what set means. i am asking from table how to fetch last
record i.e last row from a table|||On Jan 16, 4:45=A0pm, mohit <goenka.mo...@.gmail.com> wrote:
> On Jan 16, 3:28=A0pm, SB <othell...@.yahoo.com> wrote:
> > On Jan 16, 3:22=A0pm, mohit <goenka.mo...@.gmail.com> wrote:
> > > HI ALL,
> > > =A0 =A0 =A0 Suppose i did not use identity for generating sequence in =a
> > > table.Also there is no sequence no column or no primary key on a
> > > column. Then how to find last record in a table. Suppose there are 10
> > > rows. How can i fetch 10th rows record.
> > In a set there is no such thing as last record.
> Can you tell what set means. i am asking from table how to fetch last
> record i.e last row from a table
A table consists of a set of records. It is not a sequence so that you
have first or last record. A set is an unordered set of records.|||If the 'last' you mean last added then you need a column which will define
sequence of insertions. Something like 'DateAdded' or something like that.
Otherwise, you need to specify how do YOU know which record is 'last' when
you open sample data from table.
MC
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:a53c73e5-4685-4d12-8f94-5e8a1b94b5b8@.f10g2000hsf.googlegroups.com...
On Jan 16, 2:50 pm, "MC" <markoDOTculo@.gmailDOTcom> wrote:
> First you need to define 10th. What does it mean exactly? Last fetched,
> last
> by some value, last..... Without primary key you basically dont have a
> consistent approach, so some kind of definition is definitely needed here.
> MC
> "mohit" <goenka.mo...@.gmail.com> wrote in message
> news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
>
> > HI ALL,
> > Suppose i did not use identity for generating sequence in a
> > table.Also there is no sequence no column or no primary key on a
> > column. Then how to find last record in a table. Suppose there are 10
> > rows. How can i fetch 10th rows record.- Hide quoted text -
> - Show quoted text -
HI,
10th means last record. Without primary key there is no consitent
approach but suppose we dont have then how we will find.|||> Sorry yaar but its not working. When we do order by col_name desc
> the rows gets shuffle due to which answer is coming wrong
How do you know it is not working if there is no data in the row to identify
the order of insertion?
An important relational database concept is that a table is an unordered set
of rows. Rows may be returned in an arbitrary sequence unless you specify
ORDER BY. If you want data returned in the sequence in which rows were
inserted, you'll need an incrementing column like inserted datetime or
identity for the ordering.
--
Hope this helps.
Dan Guzman
SQL Server MVP
"mohit" <goenka.mohit@.gmail.com> wrote in message
news:d4d2d6c5-c6e0-4612-9f57-13accf2ff8b1@.i7g2000prf.googlegroups.com...
On Jan 16, 3:22 pm, "Uri Dimant" <u...@.iscar.co.il> wrote:
> MC
> SELECT TOP 1 col FROM tbl ORDER BY whatever DESC
> "MC" <markoDOTculo@.gmailDOTcom> wrote in message
> news:5C08A997-8EFD-4C5B-96FD-AC49EFC9DFB6@.microsoft.com...
>
> > First you need to define 10th. What does it mean exactly? Last fetched,
> > last by some value, last..... Without primary key you basically dont
> > have
> > a consistent approach, so some kind of definition is definitely needed
> > here.
> > MC
> > "mohit" <goenka.mo...@.gmail.com> wrote in message
> >news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> >> HI ALL,
> >> Suppose i did not use identity for generating sequence in a
> >> table.Also there is no sequence no column or no primary key on a
> >> column. Then how to find last record in a table. Suppose there are 10
> >> rows. How can i fetch 10th rows record.- Hide quoted text -
> - Show quoted text -
Hi,
Sorry yaar but its not working. When we do order by col_name desc
the rows gets shuffle due to which answer is coming wrong|||"mohit" <goenka.mohit@.gmail.com> wrote in message
news:7d4851f9-331b-431d-a352-c8c5d634bf95@.f3g2000hsg.googlegroups.com...
> HI ALL,
> Suppose i did not use identity for generating sequence in a
> table.Also there is no sequence no column or no primary key on a
> column. Then how to find last record in a table. Suppose there are 10
> rows. How can i fetch 10th rows record.
As others have said, w/o a primary key, there's no such thing as a "last
record" defined.
And in fact, without an ORDER BY you can never guarantee the order you'll
return the data in.
SELECT * from FOO may in fact return a different order of results at
different times.
This could be due to what's in the memory cache at the time, if the engine
decides to parallize the query across different CPUs, etc.
Now, MOST LIKELY for 10 rows, a simple "select * from FOO" will return the
data in the order it was inserted but that's absolutely no guarantee this is
true.
You may want to google the definition of a "SET" or "TABLE" within SQL.
They have no inherent order.
So sorry to say, you probably can't get the answer to the question you seek
(at least not the way it's posed.)
Greg Moore
SQL Server DBA Consulting Remote and Onsite available!
Email: sql (at) greenms.com http://www.greenms.com/sqlserver.html|||>>
10th means last record. Without primary key there is no consitent
approach but suppose we dont have then how we will find.
If you don't have a column that can tell you what "last" means, then you
could return ANY row and how would you know it wasn't the "last" row?
In SQL Server, a table is an unordered set of rows by definition. If you
say SELECT TOP 1 columns FROM table or SELECT TOP 10 columns FROM table and
you don't include an ORDER BY clause, the optimizer is free to return
whichever rows it wants... and it can change its mind when you run the query
again 5 minutes later, giving you a different set. So, if you want to
identify your "last" row, you will need to have a column that you can use to
tell SQL Server "use this column to determine last."
A
Feedback wanted: Simulating @@Identitt behavior
Traditionally, implementing an alternative for the MS SQL Server
IDENTITY in Oracle is pretty straight forward:
e.g:
---
CREATE TABLE MyTable(
ID NUMBER(10) NOT NULL,
Description VARCHAR2(128)
)
/
CREATE SEQUENCE SeqMyTable
/
CREATE OR REPLACE TRIGGER TiMyTable BEFORE INSERT ON MyTable
FOR EACH ROW
BEGIN
SELECT NVL(:new.ID, SeqMyTable.NEXTVAL) INTO :new.ID FROM DUAL;
END;
/
---
So far so good.
However, in my case I am dealing with a large application which is
running 'mixed', eg, originally designed for MS SQL Sever, and now
being adapted to run under Oracle as well. As the @.@.Identity is wildly
used, I thought of an alternative for returning the last identiry
value. As the queries themselves are already parsed, replacing all
occurrences of @.@.Identity with something else is a breeze.
So, my idea is to implement a global identity value with a package.
Can anybody tell me if the following is a good or a bad plan, and if
there are any caveats?
Thanks
Code:
---
CREATE OR REPLACE PACKAGE SomePackageName
IS
FUNCTION GetIdentity RETURN NUMBER;
PROCEDURE SetIdentity(Identity IN NUMBER);
END SomePackageName;
/
CREATE OR REPLACE PACKAGE BODY SomePackageName
IS
Identity NUMBER(10) := NULL;
FUNCTION GetIdentity
RETURN NUMBER
IS
BEGIN
RETURN Identity;
END;
PROCEDURE SetIdentity(Identity IN NUMBER)
IS
BEGIN
SomePackageName.Identity := Identity;
END;
END SomePackageName;
/
CREATE TABLE MyTable(
ID NUMBER(10) NOT NULL,
Description VARCHAR2(128)
)
/
CREATE SEQUENCE SeqMyTable
/
CREATE OR REPLACE TRIGGER TiMyTable BEFORE INSERT ON MyTable
FOR EACH ROW
BEGIN
SELECT NVL(:new.ID, SeqMyTable.NEXTVAL) INTO :new.ID FROM DUAL;
SomePackageName.SetIdentity(:new.ID);
END;
/
Application example:
---
SET SERVEROUTPUT ON;
DECLARE
NewID NUMBER(10);
BEGIN
INSERT INTO MyTable(Description) VALUES('Hello world');
NewID := SomePackageName.GetIdentity;
dbms_output.put_line('New ID = ' || TO_CHAR(NewID));
END;
/Hmmm, actually, I'd better post this in the Oracle groups. Sorry for
spamming Oracle stuff here. :)sql
IDENTITY in Oracle is pretty straight forward:
e.g:
---
CREATE TABLE MyTable(
ID NUMBER(10) NOT NULL,
Description VARCHAR2(128)
)
/
CREATE SEQUENCE SeqMyTable
/
CREATE OR REPLACE TRIGGER TiMyTable BEFORE INSERT ON MyTable
FOR EACH ROW
BEGIN
SELECT NVL(:new.ID, SeqMyTable.NEXTVAL) INTO :new.ID FROM DUAL;
END;
/
---
So far so good.
However, in my case I am dealing with a large application which is
running 'mixed', eg, originally designed for MS SQL Sever, and now
being adapted to run under Oracle as well. As the @.@.Identity is wildly
used, I thought of an alternative for returning the last identiry
value. As the queries themselves are already parsed, replacing all
occurrences of @.@.Identity with something else is a breeze.
So, my idea is to implement a global identity value with a package.
Can anybody tell me if the following is a good or a bad plan, and if
there are any caveats?
Thanks
Code:
---
CREATE OR REPLACE PACKAGE SomePackageName
IS
FUNCTION GetIdentity RETURN NUMBER;
PROCEDURE SetIdentity(Identity IN NUMBER);
END SomePackageName;
/
CREATE OR REPLACE PACKAGE BODY SomePackageName
IS
Identity NUMBER(10) := NULL;
FUNCTION GetIdentity
RETURN NUMBER
IS
BEGIN
RETURN Identity;
END;
PROCEDURE SetIdentity(Identity IN NUMBER)
IS
BEGIN
SomePackageName.Identity := Identity;
END;
END SomePackageName;
/
CREATE TABLE MyTable(
ID NUMBER(10) NOT NULL,
Description VARCHAR2(128)
)
/
CREATE SEQUENCE SeqMyTable
/
CREATE OR REPLACE TRIGGER TiMyTable BEFORE INSERT ON MyTable
FOR EACH ROW
BEGIN
SELECT NVL(:new.ID, SeqMyTable.NEXTVAL) INTO :new.ID FROM DUAL;
SomePackageName.SetIdentity(:new.ID);
END;
/
Application example:
---
SET SERVEROUTPUT ON;
DECLARE
NewID NUMBER(10);
BEGIN
INSERT INTO MyTable(Description) VALUES('Hello world');
NewID := SomePackageName.GetIdentity;
dbms_output.put_line('New ID = ' || TO_CHAR(NewID));
END;
/Hmmm, actually, I'd better post this in the Oracle groups. Sorry for
spamming Oracle stuff here. :)sql
Sunday, February 26, 2012
Fast copy of data from one table to another
I have to copy the contents of a table (6million rows) into another table on
the same instance. The target table has an identity column(PK). What is the
fastest way to do this? The instance has to remain up for the web site, and
yes, the target table is read by the web site. I was thinking a bcp out/in.
Thanks,
MichaelUse SET IDENTITY_INSERT ON/OFF to keep the identity column. There's
also a switch in the bcp utility to keep identities (-E)
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_set-set_7zas.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/coprompt/cp_bcp_61et.asp
Snake wrote:
> I have to copy the contents of a table (6million rows) into another table on
> the same instance. The target table has an identity column(PK). What is the
> fastest way to do this? The instance has to remain up for the web site, and
> yes, the target table is read by the web site. I was thinking a bcp out/in.
> Thanks,
> Michael
the same instance. The target table has an identity column(PK). What is the
fastest way to do this? The instance has to remain up for the web site, and
yes, the target table is read by the web site. I was thinking a bcp out/in.
Thanks,
MichaelUse SET IDENTITY_INSERT ON/OFF to keep the identity column. There's
also a switch in the bcp utility to keep identities (-E)
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_set-set_7zas.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/coprompt/cp_bcp_61et.asp
Snake wrote:
> I have to copy the contents of a table (6million rows) into another table on
> the same instance. The target table has an identity column(PK). What is the
> fastest way to do this? The instance has to remain up for the web site, and
> yes, the target table is read by the web site. I was thinking a bcp out/in.
> Thanks,
> Michael
Fast copy of data from one table to another
I have to copy the contents of a table (6million rows) into another table on
the same instance. The target table has an identity column(PK). What is the
fastest way to do this? The instance has to remain up for the web site, and
yes, the target table is read by the web site. I was thinking a bcp out/in.
Thanks,
Michael
Use SET IDENTITY_INSERT ON/OFF to keep the identity column. There's
also a switch in the bcp utility to keep identities (-E)
http://msdn.microsoft.com/library/de...t-set_7zas.asp
http://msdn.microsoft.com/library/de...p_bcp_61et.asp
Snake wrote:
> I have to copy the contents of a table (6million rows) into another table on
> the same instance. The target table has an identity column(PK). What is the
> fastest way to do this? The instance has to remain up for the web site, and
> yes, the target table is read by the web site. I was thinking a bcp out/in.
> Thanks,
> Michael
the same instance. The target table has an identity column(PK). What is the
fastest way to do this? The instance has to remain up for the web site, and
yes, the target table is read by the web site. I was thinking a bcp out/in.
Thanks,
Michael
Use SET IDENTITY_INSERT ON/OFF to keep the identity column. There's
also a switch in the bcp utility to keep identities (-E)
http://msdn.microsoft.com/library/de...t-set_7zas.asp
http://msdn.microsoft.com/library/de...p_bcp_61et.asp
Snake wrote:
> I have to copy the contents of a table (6million rows) into another table on
> the same instance. The target table has an identity column(PK). What is the
> fastest way to do this? The instance has to remain up for the web site, and
> yes, the target table is read by the web site. I was thinking a bcp out/in.
> Thanks,
> Michael
Fast copy of data from one table to another
I have to copy the contents of a table (6million rows) into another table on
the same instance. The target table has an identity column(PK). What is th
e
fastest way to do this? The instance has to remain up for the web site, and
yes, the target table is read by the web site. I was thinking a bcp out/in.
Thanks,
MichaelUse SET IDENTITY_INSERT ON/OFF to keep the identity column. There's
also a switch in the bcp utility to keep identities (-E)
http://msdn.microsoft.com/library/d... />
t_7zas.asp
http://msdn.microsoft.com/library/d...
1et.asp
Snake wrote:
> I have to copy the contents of a table (6million rows) into another table
on
> the same instance. The target table has an identity column(PK). What is
the
> fastest way to do this? The instance has to remain up for the web site, a
nd
> yes, the target table is read by the web site. I was thinking a bcp out/in
.
> Thanks,
> Michael
the same instance. The target table has an identity column(PK). What is th
e
fastest way to do this? The instance has to remain up for the web site, and
yes, the target table is read by the web site. I was thinking a bcp out/in.
Thanks,
MichaelUse SET IDENTITY_INSERT ON/OFF to keep the identity column. There's
also a switch in the bcp utility to keep identities (-E)
http://msdn.microsoft.com/library/d... />
t_7zas.asp
http://msdn.microsoft.com/library/d...
1et.asp
Snake wrote:
> I have to copy the contents of a table (6million rows) into another table
on
> the same instance. The target table has an identity column(PK). What is
the
> fastest way to do this? The instance has to remain up for the web site, a
nd
> yes, the target table is read by the web site. I was thinking a bcp out/in
.
> Thanks,
> Michael
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