常用SQL語句集合
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查询語句
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+ Select a random row from a database table
    `http://www.petefreitag.com/item/466.cfm <http://www.petefreitag.com/item/466.cfm>`__



元数据表操作
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.. note:: 
    SQLServer在字串前面加上N表示使用Unicode编码

+ 判断表是否存在(表名 accounts)
    
    .. code-block :: sql
        
        SELECT * FROM dbo.sysobjects WHERE id = OBJECT_ID(N'[accounts]') AND OBJECTPROPERTY(id, N'IsUserTable') = 1

+ 判断列是否存在(表名 table_name, 列名 column_name)

    .. code-block :: sql

        SELECT  *
             FROM    sys.columns
             WHERE   object_id = OBJECT_ID('table_name')
                     AND name = 'column_name'
                    
+ 判断外键約束是否存在( 約束名 constraint_name )

    .. code-block :: sql

        SELECT * 
			FROM dbo.sysobjects 
		    WHERE id = OBJECT_ID(N'constraint_name') 
			      AND OBJECTPROPERTY(id, N'IsForeignKey') = 1 

+ 判断视图是否存在(视图名 view_name)

    .. code-block :: sql

        SELECT TABLE_NAME FROM INFORMATION_SCHEMA.VIEWS WHERE TABLE_NAME = N'view_name' 

+ 判断存储过程是否存在

    .. code-block :: sql

        SELECT * FROM sysobjects WHERE name = 'usp' and type='P'