CREATEFUNCTIONget_multiple_values()RETURNSVARCHAR(255)BEGINDECLAREdoneINTDEFAULTFALSE;DECLAREaINT;DECLAREbINT;DECLAREcINT;DECLAREcurCURSORFORSELECTid,name,ageFROMusers;DECLARECONTINUEHANDLERFORNOTFOUNDSETdone=TRUE;OPENcur;read_loop:LOOPFETCHcurINTOa,b,c;IFdoneTHENLEAVEread_loop;ENDIF;-- 在这里可以做一些...
CREATE FUNCTION get_multiple_values() RETURNS CHAR BEGIN DECLARE value1 CHAR; DECLARE value2 CHAR;-- 逻辑处理 SET value1 = 'Value1'; SET value2 = 'Value2';RETURN CONCAT(value1, ',', value2);END 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 在上面的代码中,我们创建了一...
data is found at the path given; this clause takes one of the following values: NULL ON EMPTY: The function returns NULL; this is the default ON EMPTYbehavior. DEFAULT value ON EMPTY: the provided value is returned. The values type must match that of the return type. ERROR ...
MySQL procedure 与 function 的区别 1. 只能说是看各自的习惯的,用procedure可以实现的,大部分用函数都可以的,所以有些package中函数的实现一个,过程的实现一个。 2.考虑是使用函数还是使用存储过程可以根据以下方面: 从参数的返回情况来看:如果返回多个参数值最好使用存储过程,如果只有一个返回值的话可以使用函数;...
This function takes a LineString geometry and a fractional distance in the range (0.0, 1.0] and returns the MultiPoint consisting of the LineString start point, plus Point values along the LineString at each fraction of the distance from its start point to its endpoint. It can be used to...
Return Value:FALSE if the first query fails PHP Version:5+ Example - Procedural style Perform multiple queries against the database: <?php $con = mysqli_connect("localhost","my_user","my_password","my_db"); if(mysqli_connect_errno()) { ...
';varmodSqlParams=['菜鸟移动站','https://m.runoob.com',6];//改connection.query(modSql,modSqlParams,function(err,result){if(err){console.log('[UPDATE ERROR] -',err.message);return;}console.log('---UPDATE---');console.log('UPDATE affectedRows',result.affectedRows);console.log('--...
Returns a count of the number of non-NULL values of expr in the rows retrieved by a SELECT statement. The result is a BIGINT value. If there are no matching rows,COUNT()returns 0.COUNT(NULL)returns 0. This function executes as a window function if over_clause is present. over_clause...
【3】如果表有一个multiple-column索引，任何一个索引的最左前缀可以通过使用优化器来查找行。【4】查询...
本章列出了当你用任何主机语言调用MySQL时可能出现的错误。首先列出了服务器错误消息。其次列出了客户端程序消息 B.1. 服务器错误代码和消息 服务器错误信息来自下述源文件: · 错误消息信息列在share/errmsg.txt文件中。“%d”和“%s”分别代表编号和字符串,显示时,它们将被消息值取代。 · 错误值列在share/errm...