cnblogs/dcrenl/SQL语法.html

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2024-09-24 12:43:01 +08:00
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<div>distinct :去掉查询结果集中的重复记录 例如:SELECT &nbsp;DISTINCT&nbsp;* &nbsp; FROM&nbsp;Table</div>
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<div>truncate table : 清空表,自增ID重新开始 例: TRUNCATE TABLETablename</div>
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<div>INSERT INTO 后使用SELECT @@IDENTITY 会反回自增ID</div>
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<div>DUMP TRANSACTION JobIntern WITH NO_LOG删除数据库日志2008中已取消这个功能</div>
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<div><span style="font-family: 'Segoe UI',Verdana,Arial; font-size: 12px;"><span style="line-height: normal;">返回受上一语句影响的行数。如果行数大于 20亿请使用</span></span><a href="http://msdn.microsoft.com/zh-cn/library/ms181406(v=SQL.90).aspx" target="_blank">ROWCOUNT_BIG</a></div>
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<div>UPDATE t_pub_param SET ParamValue = @ParamValue WHEREParamName = @ParamName</div>
<div>IF @@rowcount &lt; 1</div>
<div>BEGIN</div>
<div>INSERT t_pub_param(ParamName, ParamValue) values(@ParamName,@ParamValue)</div>
<div>END</div>
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<div>EXISTS指定一个子查询检测行的存在</div>
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<div>if(exists(select * from&nbsp; <span style="line-height: 21px;">t_pub_param&nbsp;</span>where&nbsp;<span style="line-height: 21px;">ParamValue= @ParamValue</span>&nbsp;))</div>
<div>BEGIN</div>
<div>SET @re = 1</div>
<div>END</div>
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<div>ISDATE() &nbsp;--函数判断所给定的表达式是否为合理日期</div>
<div>语法</div>
<div>ISDATE ( expression )</div>
<div>参数</div>
<div>expression</div>
<div>一个表达式将要验证它是否为一个日期。expression 是任何返回 varchar 数据类型的表达式。</div>
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<div>返回值</div>
<div>0表示非日期类型空串[''],空值[null]都为0</div>
<div>1表示日期类型</div>
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