How to write an SQL statement that changes the field type to "ID" and sets this field as the primary key?

Subject:   How to write an SQL statement that modifies the field type to "ID" and sets this field as the primary key ?? Author:   China_skag () Level 1:     Reputation value:   100 Forum:   MS-SQL server problems Problem points:   20 Replies:   11 Posting time:   2006-7-28 14:26:56               As the question!

	Reply:Louisxiv)() Credit: 100	2006-7-28 14:38:54	Score: 0
?	Unable to alter a column into identity Field
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	Reply:Liangpei2008 (Xiaojie)() Credit: 100	2006-7-28 14:50:59	Score: 0
?	Deleted and rebuilt Fields
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	Reply:China_skag ()() Credit: 100	2006-7-28 14:56:23	Score: 0
?	Waiting online .....
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	Reply:Hellowork (one or two breeze)() Credit: 100	2006-7-28 15:06:53	Score: 0
?	Columns to be identified as identity columns can only be deleted first and then added with the same name. ---- Delete a column Alter table tablename drop column ID Go ---- Add the identity column Alter table tablename add ID int identity (1, 1) Go ---- Set the identity column as the primary key Alter table tablename add constraint [pk_tablename] primary key clustered ([ID])
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	Reply:China_skag ()() Credit: 100	2006-7-28 15:39:34	Score: 0
?	What does [pk_tablename] mean? If there is another table: Title Column name: ID name type content addtime Where ID is int type I want to change the ID to identity and primary key. How can I write an SQL statement? I wrote the following, right? Please advise. Alter table title drop column ID Go Alter table title add ID int identity (1, 1) Go Alter table title add constraint [pk_tablename] primary key clustered ([ID])
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	Reply:Hellowork (one or two breeze)() Credit: 100	2006-7-28 15:45:07	Score: 0
?	Replace tablename in pk_tablename with title. For example: Alter table title add constraint [pk_title] primary key clustered ([ID]) Tablename is only a placeholder. It is replaced with a specific table object name.
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	Reply:Louisxiv)() Credit: 100	2006-7-28 15:45:26	Score: 0
?	What does [pk_tablename] mean? ----------------------- It just a name for the primary key, you can name it as any string you can imagine.
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	Reply:China_skag ()() Credit: 100	2006-7-28 15:48:55	Score: 0
?	Thank you very much, hellowork (one or two breeze), louisxiv (night god )!
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	Reply:Hellowork (one or two breeze)() Credit: 100	2006-7-28 15:51:11	Score: 0
?	[Pk_title] is the name of the primary key constraint. In sqlserver, primary keys, foreign keys, default values, triggers, stored procedures, and functions are all objects. You must name these objects. sqlserver can use these names to manage them. Generally, their class abbreviations are used as the prefix of the object name when naming objects, so that you can know where the object is through this prefix. therefore, [pk_title] is the name of the primary key, and PK is the abbreviation of primarykey.
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	Reply:China_skag ()() Credit: 100	2006-7-28 15:57:08	Score: 0
?	Oh! It turns out like this. Thank you!
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	Reply:China_skag ()() Credit: 100	2006-7-28 15:58:35	Score: 0
?	Alter table title drop column ID Go Alter table title add ID int identity (1, 1) Go Alter table title add constraint [pk_title] primary key clustered ([ID])