Validate date in MySQL using custom function

Let’s create a custom function to validate date in MySQL -

mysql> set global log_bin_trust_function_creators=1;
Query OK, 0 rows affected (0.03 sec)
mysql> delimiter //
mysql> create function isValidDate(actualDate varchar(255)) returns int
   -> begin
   -> declare flag int;
   -> if (select length(date(actualDate)) IS NOT NULL ) then
   -> set flag = 1;
   -> else
   -> set flag = 0;
   -> end if;
   -> return flag;
   -> end
   -> //
Query OK, 0 rows affected (0.11 sec)
mysql> delimiter ;

Case 1 −

When the parameters When it is a null value, the date to be checked is not the actual date. Calling the function using a SELECT statement −

mysql> select isValidDate(NULL);

This will produce the following output which is not a date -

+-------------------+
| isValidDate(NULL) |
+-------------------+
| 0                 |
+-------------------+
1 row in set (0.05 sec)

Case 2 -

When the argument is an actual date value time. Calling the function using a SELECT statement -

mysql> select isValidDate('2019-10-21');

This will produce the following output i.e. 1, actual date -

+---------------------------+
| isValidDate('2019-10-21') |
+---------------------------+
| 1                         |
+---------------------------+
1 row in set (0.00 sec)

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