How to mask data fields in MySQL?

To mask data fields, use CONCAT() along with REPEAT(). Here, we will mask data fields with #. Let us first create a −

mysql> create table DemoTable1410
   -> (
   -> Password varchar(80)
   -> );
Query OK, 0 rows affected (0.51 sec)

Insert some records in the table using insert −

mysql> insert into DemoTable1410 values('John12345678');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable1410 values('Carol_897');
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable1410 values('David_5647383');
Query OK, 1 row affected (0.17 sec)

Display all records from the table using select −

mysql> select * from DemoTable1410;

This will produce the following output −

+---------------+
| Password      |
+---------------+
| John12345678  |
| Carol_897     |
| David_5647383 |
+---------------+
3 rows in set (0.00 sec)

Here is the query to mask data fields in MySQL −

mysql> update DemoTable1410
   -> set Password=concat(substr(Password, 1, 5), repeat('#', char_length(Password) - 5));
Query OK, 3 rows affected (0.16 sec)
Rows matched: 3  Changed: 3 Warnings: 0

Let us check the table records once again −

mysql> select * from DemoTable1410;

This will produce the following output −

+---------------+
| Password      |
+---------------+
| John1#######  |
| Carol####     |
| David######## |
+---------------+
3 rows in set (0.00 sec)