MySQL CAST as DATE

Question

I\'m trying to understand what casting a value to the DATE type in MySQL does. Here are some things I have tried:

SELECT CAST(\'3\' AS DATE);
-- null

SELECT          


        

Answer 1

Checking the source code of MySQL 5.6 CAST() and CONVERT() calls to the same internal function Item_date_typecast, DATE() calls to Item_date_typecast too.

In conclusion there is no difference between DATE(expr) function and the CAST(expr AS DATE).

Refs:

https://github.com/mysql/mysql-server/blob/5.6/sql/sql_yacc.yy

https://github.com/mysql/mysql-server/blob/5.6/sql/item_create.cc