How do I validate a MYSQL Date field for NULL/ EMPTY?

Question

I'm developing a MYSQL Stored Proc, and in that I need to validate a date field as follows,

IF (dt_wedding_date<>'') THEN
     IF (int_days_to_wedding>0) THEN
      SET vc_wedding ='F';
    ELSE
      SET vc_wedding ='P';
    END IF;
  ELSE
    SET vc_wedding = 'NA';
  END IF;

But when the dt_wedding_date is null it never goes to the ELSE part. I tried "is null", "is not null", ">", <>, trim functions, nothing worked.

Any idea how to evaluate this date field for nulls/empty?

Answer 1

try isnull function, I tried it on my local mysql

mysql> select * from data_test;
+----+------------+
| id | gmt_create |
+----+------------+
|  1 | NULL       |
+----+------------+
1 row in set (0.00 sec)

mysql> select id, isnull(gmt_create) from data_test;
+----+--------------------+
| id | isnull(gmt_create) |
+----+--------------------+
|  1 |                  1 |
+----+--------------------+
1 row in set (0.00 sec)

mysql> 

from the w3c reference

MySQL does have an ISNULL() function. However, it works a little bit different from Microsoft's ISNULL() function.