How to update data in a MySQL database without removing the old data?

For this, you can use UPDATE and concatenate the new data with the old one to save the old data as well −

update yourTableName set yourColumnName=concat(yourColumnName,",yourValue");

Let us first create a table −

mysql> create table DemoTable
-> (
-> CustomerName varchar(100)
-> );
Query OK, 0 rows affected (0.54 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values('Chris');
Query OK, 1 row affected (0.24 sec)

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

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

Display all records from the table using select statement −

mysql> select *from DemoTable;

Output

This will produce the following output −

+--------------+
| CustomerName |
+--------------+
| Chris        |
| David        |
| Sam          |
+--------------+
3 rows in set (0.00 sec)

Following is the query to update new data in the database without removing old data −

mysql> update DemoTable set CustomerName=concat(CustomerName,",Brown");
Query OK, 3 rows affected (0.14 sec)
Rows matched: 3 Changed: 3 Warnings: 0

Let us check the table records once again −

mysql> select *from DemoTable;

Output

This will produce the following output −

+--------------+
| CustomerName |
+--------------+
| Chris,Brown  |
| David,Brown  |
| Sam,Brown    |
+--------------+
3 rows in set (0.00 sec)