MSSQL --- MSDN 刪除主索引鍵

請參考MSDN:刪除主索引鍵
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USE AdventureWorks2012;
GO
-- Return the name of primary key.
SELECT name
FROM sys.key_constraints
WHERE type = 'PK' AND OBJECT_NAME(parent_object_id) = N'TransactionHistoryArchive';
GO
-- Delete the primary key constraint.
ALTER TABLE Production.TransactionHistoryArchive
DROP CONSTRAINT PK_TransactionHistoryArchive_TransactionID;
GO

參考引用來源:SQL SERVER – How to Drop Primary Key Contraint
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SQL SERVER – How to Drop Primary Key Contraint
One area that always, unfailingly pulls my interest is SQL Server Errors and their solution. I enjoy the challenging task of passing through the maze of error to find a way out with a perfect solution. However, when I received the following error from one of my regular readers, I was a little stumped at first! After some online probing, I figured out that it was actually syntax from MySql and not SQL Server. The reader encountered error when he ran the following query.

ALTER TABLE Table1
DROP PRIMARY KEY
GO

Msg 156, Level 15, State 1, Line 3
Incorrect syntax near the keyword ‘PRIMARY’.

As mentioned earlier, this syntax is for MySql, not SQL Server. If you want to drop primary key constraint in SQL Server, run the following query.

ALTER TABLE Table1
DROP CONSTRAINT PK_Table1_Col1
GO

Let us now pursue the complete example. First, we will create a table that has primary key. Next, we will drop the primary key successfully using the correct syntax of SQL Server.

CREATE TABLE Table1(
Col1 INT NOT NULL,
Col2 VARCHAR(100)
CONSTRAINT PK_Table1_Col1 PRIMARY KEY CLUSTERED (
Col1 ASC)
)
GO

/* For SQL Server/Oracle/MS ACCESS */
ALTER TABLE Table1
DROP CONSTRAINT PK_Table1_Col1
GO

/* For MySql */
ALTER TABLE Table1
DROP PRIMARY KEY
GO

I hope this example lucidly explains how to drop primary key. This, no doubt, is a very simple and basic explanation, but when I chanced upon the error message it aroused curiosity in me.  As you all know by now I love sharing new issues and ideas with my readers. So I have included this interesting error in my blog.

Let me have your feedback on this post and also, do feel free to share with me your ideas as well!