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sdw
Starting Member
6 Posts |
 Posted - 2010-05-03 : 03:39:53
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| Hi all,I have a table which contains the following columns:--Emp_ID as primary key-Emp_Name-Emp_DeptHow can I update the table to make the Emp_Dept column primary key, I need to make it using Alter Table statement. |
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DBA in the making
Aged Yak Warrior
638 Posts |
Posted - 2010-05-03 : 06:57:13
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| [code]ALTER TABLE tableName DROP CONSTRAINT PK_tableName_1GOALTER TABLE tableName ADD CONSTRAINT PK_tableName_2 PRIMARY KEY (Emp_Dept)GO[/code]WHERE:tableName is the name of the tablePK_tableName_1 is the name of the existing PRIMARY KEY CONSTRAINTPK_tableName_2 is the name of the new PRIMARY KEY CONSTRAINTHowever, this doesn't seem very logical. It's unlikely that every employee would have a unique department. Perhaps you meant to you meant to add the Emp_Dept to the primary key. ie, a combined key, using Emp_ID and Emp_Dept. In that case, you can use this instead:[code]ALTER TABLE tableName ADD CONSTRAINT PK_tableName_2 PRIMARY KEY (Emp_ID, Emp_Dept)GO[/code]------------------------------------------------------------------------------------Any and all code contained within this post comes with a 100% money back guarantee. |
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visakh16
Very Important crosS Applying yaK Herder
52326 Posts |
Posted - 2010-05-03 : 10:04:28
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| unless all employees are linked to unique department and also all employees do have a department you cant make it primary key. Primary key field should be a unique non NULL valued field.------------------------------------------------------------------------------------------------------SQL Server MVPhttp://visakhm.blogspot.com/ |
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Add new primary key on table