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Posted by David Portas on 10/01/88 11:40
anonieko@hotmail.com wrote:
> > This is a common problem with some solution
> >
> >
>
> /***********************************************************************************
> *
> * Problem:
> * Determine the Duplicated Records in a table using single SELECT.
> *
> * We shall be using Northwind database, add some duplicate records.
> *
> * Here we want to know if 2 columns (CompanyName,
> * PHone) are duplicated in a table.
> *
> *
> * ShipperID CompanyName Phone
> * ----------- ------------------------- ------------------
> * 1 Speedy Express (503) 555-9831
> * 2 United Package (503) 555-3199
> * 3 Federal Shipping (503) 555-9931
> * 4 Federal Shipping (503) 555-9931
> * 5 Speedy Express (503) 555-9831
> * 6 Federal Shipping (503) 555-9931
> *
> *
> *
> ****************************************************/
>
> ==================================================
>
> SOLUTION 1: Gives me the IDs that are duplicated.
>
> ==================================================
>
> SELECT
> ShipperID, CompanyName, Phone
> FROM
> SHIPPERS
> WHERE
> EXISTS (
> SELECT
> NULL
> FROM
> SHIPPERS b
> WHERE
> b.CompanyName = SHIPPERS.CompanyName
> AND b.Phone = SHIPPERS.Phone
> GROUP BY
> b.CompanyName, b.Phone
> HAVING
> SHIPPERS.ShipperID < MAX( b.ShipperID )
> )
>
> /* ********************
> * Output results
> ********************/
>
> ShipperID CompanyName Phone
>
> ----------- ----------------------------------------
> ------------------------
> 1 Speedy Express (503) 555-9831
> 3 Federal Shipping (503) 555-9931
> 4 Federal Shipping (503) 555-9931
>
> (3 row(s) affected)
>
>
>
> =============================================================
>
> SOLUTION 2: Gives me the data which are duplicate but
> not the IDs
>
> =============================================================
>
>
> SELECT
> CompanyName, Phone
> FROM
> SHIPPERS
> GROUP BY
> CompanyName, Phone
> HAVING
> COUNT(*) > 1
>
>
> /* ********************
> * Output results
> ********************/
>
>
>
> CompanyName Phone
> ---------------------------------------- ------------------------
> Speedy Express (503) 555-9831
> Federal Shipping (503) 555-9931
>
> (2 row(s) affected)
Those aren't solutions, they are diagnostics. The solution is to fix
the stupid design of the Shippers table by adding a proper key.
:-)
--
David Portas, SQL Server MVP
Whenever possible please post enough code to reproduce your problem.
Including CREATE TABLE and INSERT statements usually helps.
State what version of SQL Server you are using and specify the content
of any error messages.
SQL Server Books Online:
http://msdn2.microsoft.com/library/ms130214(en-US,SQL.90).aspx
--
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