sql给已有表添加主键

/*ALTER TABLE [dbo].[cg_YearAssessZp] ALTER COLUMN YearAssessZpGUID UNIQUEIDENTIFIER  NOT NULL;ALTER TABLE [dbo].[cg_YADetailHistory] ADD CONSTRAINT [PKC_cg_YADetailHistory] PRIMARY KEY CLUSTERED  ([YearAssessZpGUID]) ON [PRIMARY];*/IF EXISTS(SELECT TOP 1 1 FROM sysobjects WHERE id=OBJECT_ID('proc_AddPrimaryKey') AND type='P')DROP PROCEDURE proc_AddPrimaryKey;GOCREATE PROCEDURE proc_AddPrimaryKey    (      @tablename VARCHAR(40) ,      @pkname VARCHAR(40)    )AS     BEGIN        IF NOT EXISTS ( SELECT TOP 1                                1                        FROM    sys.columns                        WHERE   object_id = OBJECT_ID(@tablename)                                AND name = @pkname )             BEGIN                PRINT 'Not Exists PKName'                RETURN            END                DECLARE @coltype VARCHAR(40);        SELECT  @coltype = b.name        FROM    syscolumns a ,                systypes b        WHERE   a.id = OBJECT_ID('test_test')                AND a.name = 'id'                AND a.xtype = b.xtype;                                   IF NOT EXISTS ( SELECT  c.name                        FROM    sys.indexes a                                INNER JOIN sys.index_columns b ON a.object_id = b.object_id                                                              AND a.index_id = b.index_id                                INNER JOIN sys.columns c ON b.column_id = c.column_id                                                            AND b.object_id = c.object_id                        WHERE   c.object_id = OBJECT_ID(@tablename)                                AND c.name = @pkname )             BEGINEXECUTE('ALTER TABLE [dbo].['+@tablename+'] ALTER COLUMN '+ @pkname +' '+ @coltype +'  NOT NULL;');                            EXECUTE('ALTER TABLE [dbo].['+@tablename+'] ADD CONSTRAINT [PKC_'+@tablename+'] PRIMARY KEY CLUSTERED  (['+ @pkname +']) ON [PRIMARY];')                                PRINT 'Added PK Sussess(table:' + @tablename + ', column:' + @pkname            + ')'   ;                             ENDELSE PRINT 'PK Already Existed(table:' + @tablename + ', column:' + @pkname            + ')'   ;         RETURN     END;GO/*test data*/IF EXISTS(SELECT TOP 1 1 FROM sysobjects WHERE id=OBJECT_ID('test_test') AND type='U')DROP TABLE test_test;GOCREATE TABLE test_test (id UNIQUEIDENTIFIER , NAME VARCHAR(40));EXEC proc_AddPrimaryKey 'test_test','id';