The CONVERT is the one inducing the inefficiency of the index-CodePudding

Home > database > The CONVERT is the one inducing the inefficiency of the index

The CONVERT is the one inducing the inefficiency of the index

Time：09-24

SELECT * FROM table1 WHERE a='1';
SELECT * FROM table1 WHERE a=the CONVERT (1, CHAR);

Field is of type VARCHAR, has constructed the index, the first statement can use index, but the second was useless,

CodePudding user response:

Varchar and char type is not the same;
Is not the same as the character set can also cause index expires

Page link：https//www.codepudding.com/database/27135.html

Prev:Show me a great god door, multiple tables in MySQL inner join, data volume is not large, why don

Next:Mysql user password

Tags：

MySQL

Links：
CodePudding