MySQL query to update string field by concatenating to it?

For concatenating a string field, use CONCAT() function. Let us first create a table −

mysql> create table DemoTable
   -> (
   -> SequenceId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> StudentId varchar(100)
   -> );
Query OK, 0 rows affected (0.59 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable(StudentId) values('STU');
Query OK, 1 row affected (0.14 sec)

mysql> insert into DemoTable(StudentId) values('STU1');
Query OK, 1 row affected (0.18 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

Output

+------------+-----------+
| SequenceId | StudentId |
+------------+-----------+
| 1          | STU       |
| 2          | STU1      |
+------------+-----------+
2 rows in set (0.00 sec)

Here is the query to update string field by concatenating to it −

mysql> update DemoTable
   -> set StudentId=concat(StudentId,'-','101');
Query OK, 2 rows affected (0.14 sec)
Rows matched: 2 Changed: 2 Warnings: 0

Let us check all the records once again from the table −

mysql> select *from DemoTable;

Output

+------------+-----------+
| SequenceId | StudentId |
+------------+-----------+
| 1          | STU-101   |
| 2          | STU1-101  |
+------------+-----------+
2 rows in set (0.00 sec)