Concatenate two columns when one of such column values is null in MySQL

To avoid any issues while running a query, use IFNULL(). Let us first create a table −

mysql> create table DemoTable1793
     (
     StudentFirstName varchar(20),
     StudentLastName varchar(20)
     );
Query OK, 0 rows affected (0.00 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1793 values('John','Smith');
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1793 values('Carol',NULL);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1793 values(NULL,'Brown');
Query OK, 1 row affected (0.00 sec)

Display all records from the table using select statement −

mysql> select * from DemoTable1793;

This will produce the following output −

+------------------+-----------------+
| StudentFirstName | StudentLastName |
+------------------+-----------------+
| John             |           Smith |
| Carol            |            NULL |
| NULL             |           Brown |
+------------------+-----------------+
3 rows in set (0.00 sec)

Here is the query to concatenate two columns when one of such column values is null −

mysql> select concat(ifnull(StudentFirstName,''),ifnull(StudentLastName,'')) from DemoTable1793;

This will produce the following output −

+----------------------------------------------------------------+
| concat(ifnull(StudentFirstName,''),ifnull(StudentLastName,'')) |
+----------------------------------------------------------------+
| JohnSmith                                                      |
| Carol                                                          |
| Brown                                                          |
+----------------------------------------------------------------+
3 rows in set (0.00 sec)