mysql - UPDATE a column based on the value of another column in the same table

Question

UPDATE a column REGNO based on the value of another column SERIAL and YEAR_ADMITTED in the same table.

SERIAL | REGNO | YEAR_ADMITTED | FULL_NAME
---------------------------------------------
0001   |       |  2011         | LUM Anye
1009   |       |  2014         | Hans Musah

Answer 1

As per Fabricator's suggestion amended to include a where clause so you don't overwrite and existing REGNO.

UPDATE students SET REGNO = CONCAT( year_admitted, SERIAL )
WHERE REGNO IS NULL OR REGNO=''

You may have to CAST year_admitted if it is not already a string

UPDATE students SET REGNO = CONCAT( CAST(year_admitted as CHAR), SERIAL )
WHERE REGNO IS NULL OR REGNO=''