mysql中如何更新一个字段的值为它本身的值连接上一个字符串

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mysql中如何更新一个字段的值为它本身的值连接上一个字符串_MySQL

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Jun 01, 2016 pm 01:31 PM

mysqlhowstring

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mysql中如何更新一个字段的值为它本身的值连接上一个字符串

CONCAT(str1,str2,...) 返回结果为连接参数产生的字符串。

如有任何一个参数为NULL ，则返回值为 NULL。

或许有一个或多个参数。如果所有参数均为非二进制字符串，则结果为非二进制字符串。如果自变量中含有任一二进制字符串，则结果为一个二进制字符串。一个数字参数被转化为与之相等的二进制字符串格式；若要避免这种情况，可使用显式类型 cast, 例如：

SELECT CONCAT(CAST(int_col AS CHAR), char_col)mysql> SELECT CONCAT(&#39;My&#39;, &#39;S&#39;, &#39;QL&#39;);        -> &#39;MySQL&#39;mysql> SELECT CONCAT(&#39;My&#39;, NULL, &#39;QL&#39;);        -> NULLmysql> SELECT CONCAT(14.3);        -> &#39;14.3&#39;eg:[sql] UPDATE admin_role SET auth=CONCAT(auth,&#39;,55,56&#39;) WHERE id IN (1,3,4);

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