Things to note about MySQL's varchar type, mysqlvarchar_PHP tutorial

Notes on MySQL’s varchar type, mysqlvarchar

I discovered such a problem at work a few days ago: when the type of a field is varchar, the value saved in the field is similar to '100, 200, 300' and '100' or '100,400'. You will make such mistakes when writing SQL statements, for example:

select id,provinceid from admin where provinceid in ('100'<span>);

select id</span>,provinceid from admin where provinceid in (100);

You will find that the query results of the above two SQLs are not the same, and the correct SQL is the second one. Because the values ​​stored in the field are similar to '100, 200, 300', not '100', '200', '300', the SQL in item 2 is correct.

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