How to extract the digit part from the string in MySQL?

Let us first create a table −

mysql> create table DemoTable
   -> (
   -> StudentId varchar(100)
   -> );
Query OK, 0 rows affected (0.71 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values('John19383');
Query OK, 1 row affected (0.18 sec)

mysql> insert into DemoTable values('Carol9999');
Query OK, 1 row affected (0.16 sec)

mysql> insert into DemoTable values('David123456');
Query OK, 1 row affected (0.15 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

Output

This will produce the following output −

+-------------+
| StudentId   |
+-------------+
| John19383   |
| Carol9999   |
| David123456 |
+-------------+
3 rows in set (0.00 sec)

Following is the query to extract the digit part from the string −

mysql> SELECT replace(reverse(FORMAT(reverse(StudentId), 0)), ',', '') as OnlyDigit from DemoTable;

Output

This will produce the following output −

+-----------+
| OnlyDigit |
+-----------+
| 19383     |
| 9999      |
| 123456    |
+-----------+
3 rows in set (0.05 sec)