Subject Written By Posted Update from Multiple Rows Alan Little June 15, 2009 07:49AM Sorry, you can't reply to this topic. It has been closed.
当MySQL优化部分查询,并转换为一个常量时,使用这些类型访问.如将主键置与where列表中,MySQL就能将该查询替换为一个常量.需要注意的是system是const的特殊类型,当查询的表只有一行的情况下使用system. NULL: MySQL在优化过程中分解语句,执行时不用访问表或者索引. possible_keys: MySQL能够使用那个索引找到匹配的行,查...
INSERT ... ON DUPLICATE KEY UPDATE Syntax可参见官方网站:insert-on-duplicate 功能: 表示插入时,如果遇到了主键重复或唯一索引重复,则不执行插入操作,而是执行更新操作; 注意点: 这种方式的批量更新,不是sql的规范,而是mysql特有的; 只能针对唯一索引(UNIQUE index)和主键索引(RIMARY KEY)进行更新; 对于自增主键...
Introduction to MySQL UPDATE statement# We use the UPDATE statement to update existing data in a table. We can use the UPDATE statement to change column values of a single row, a group of rows, or all rows in a table. The following illustrates the syntax of the MySQL UPDATE statement: ...
TheUPDATEstatement is used to update existing data in tables. It can be used to change column values of a single row, a group of rows or all rows in a table. The following illustrates the MySQLUPDATEstatement syntax: UPDATE [LOW_ PRIORITY] [IGNORE] table_name [, table_name...] SET ...
Bug #15028 Update multiple tables updates more rows than expected Submitted: 17 Nov 2005 17:21Modified: 8 Dec 2005 23:53 Reporter: Dan Julson Email Updates: Status: Closed Impact on me: None Category: MySQL ServerSeverity: S3 (Non-critical) Version: 5.0.17-BK, 5.0.15, 4.1.14/5.0....
when you want to update multiple rows with different values, the system must know, which rows you want to update with which values. This means, you need a condition for every row you want to update. something like: UPDATE tab set a=1 where id=50, set b=5 where id=75, set a=7 ...
原因:For the multiple-table syntax, UPDATE updates rows in each table named in table_references that satisfy the conditions. In this case, ORDER BY and LIMIT cannot be used.(MySQL 文档) 翻译一下就是对于多表语法,UPDATE会更新table_references中每个表中满足条件的行。在这种情况下,不能使用ORDER ...
ha_rowsUpdateRowsIterator::found_rows()const inline bool UpdateRowsIterator::Init() overridevirtual Initialize or reinitialize the iterator. You must always call Init() before trying a Read() (but Init() does not imply Read()). You can call Init() multiple times; subsequent calls will rewi...
"UPDATE `items` SET `order`=??? WHERE `list`=123 ORDER by `order` Any Help would be greatly appriciated. TT Edited 1 time(s). Last edit at 10/15/2005 01:13PM by Theo Tonge. Subject Written By Posted Update Multiple Rows with incrementing values Theo...