SELECT TASK_ID FROM LS_TASK GROUP BY TASK_ID 1.1.1.3. 合理使用NOT IN和NOT EXISTS 优化说明 1. 子查询结果集较小时(个数或者百数之内),使用NOT IN会优于NOT EXISTS。 2. 子查询具有一定复杂度时(即SQL关联关系较多,例如子查询中包含多个表查询),使用NOT IN会优于NOT EXISTS。 3. 其他情况下NOT EXI...
mysql instr替代in sql用什么替代in 1、IN 操作符 用IN写出来的SQL的优点是比较容易写及清晰易懂,这比较适合现代软件开发的风格。但是用IN的SQL性能总是比较低的,从Oracle执行的步骤来分析用IN的SQL与不用IN的SQL有以下区别: ORACLE试图将其转换成多个表的连接,如果转换不成功则先执行IN里面的子查询,再查询外层...
More SQL in MySQL 8.0 https://www.slideshare.net/NorvaldRyeng/more-sql-in-mysql-80 Subject Views Written By Posted More SQL in MySQL 8.0 1169 Edwin Desouza November 06, 2018 07:28PM Sorry, you can't reply to this topic. It has been closed. ...
More SQL in MySQL 8.0 https://www.slideshare.net/NorvaldRyeng/more-sql-in-mysql-80 Subject Views Written By Posted More SQL in MySQL 8.0 1156 Edwin Desouza November 06, 2018 07:28PM Sorry, you can't reply to this topic. It has been closed. ...
参考:http://www.lijiejie.com/mysql-injection-bypass-waf limit过滤逗号,,使用offset绕过; limit x,y ;从第x+1个数据开始取,取y个数据; limit x offset y ;从第y+1个数据开始取,去x个数据;报错注入有时限制显示字符数,利用第二个来搞即可; 过滤逗号,,使用join来绕过; 不能使用大小于大于>小于<符号,...
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TMySQLConnection.SetOption: find defined name of option constant per RTTI and show it in error message (when setting failed) committed: 18 Nov 2024 07:40compiled: 18 Nov 2024 08:25 64bit build23.9 MB≃ Revision 12.8.0.6954 Issue #1426andissue #1768: minor: do not try to set MARIADB_...
mysql使用in超过1000会报错吗 mysql in_use 大于0,MySQL基础引擎sql语句增删改查引擎MySQL5.5.5以前默认是MylSAM以后默认是i、InnDBshowengines\GMylSAM读取效率高读取效率高不支持事务表锁锁着整张表支持全文索引不支持外键InnoDB安全性高支持事务同时操作多个数据但是其