[Mysql] calculates the item that is different from the last X days. The SQL statement compares the date and mysqlsql

[Mysql] calculates the item that is different from the last X days. The SQL statement compares the date and mysqlsql

For the following testtable table

Use the following SQL statement:

Select * from testtablewheretimestampdiff (year, date, now () <30

In this method, the query is successful even if the date field is of the varchar type.

In the timestampdiff function, the first field is the unit and can be changed to second, day, month, etc.

The following query method, considering that the difference between 1985 and the current one is 30 years, is simple, but if the date is changed, for example, next year, this statement must be changed to 1986-1-1.

In addition, if the date field is saved in the varchar type for various reasons,

The query is not successful at all.

Select * from testtablewhere date> '2014-1-1'