Update data in database using SQL - mysql

Question

I have one table in my database. Field of table are describe below.
ID | NAME | QUALIFICATION
1 | ABC | Phd
2 | XYZ | MBA
3 | ADS | MBA
Now my problem is related to update QUALIFICATION record. Suppose if I update record of QUALIFICATION, it should be append new value to existing value.
For example, I am going to update record of id=1. Now I update "QUALIFICATION" MCA then it should add MCA to the existing record Phd, separated with comma. Output will looks like below.
ID | NAME | QUALIFICATION
1 | ABC | Phd,MCA
2 | XYZ | MBA
3 | ADS | MBA
When "QUALIFICATION" is null then the update should not be add comma before MCA.

Answer 1

Thats a bad database design never store the data as comma separated string, this will make things messy in future.
You should think of normalizing the table something as for the student your table should look like
- id primary key auto_incremented
- name
- other columns related to student
Then another table as student_qualification
- id primary key auto_incremented
- id_student ( id from student table)
- qualification
So for each student you can add as many qualification as possible to this table and can easily do add/edit/delete data
You can later easily retrieve data using simple joining the table.

Answer 2

first u have to select your existing value of Qualification column
that u want to update
Using
select qualification from tb_name where id = 1
Using above query u will get your qualification column value
suppose in
$qulification
Now update that row using
update set tb_name set qualification = '".$qualification."."your new value" where id = 1

Answer 3

May you can try this
update employee set qualification = qualification || ',MCA' where id = 1
the above will work in oracle
EDIT:
Then you can have the case statement with it
update employee set qualification = case when qualification is null then
'MCA' else qualification || ',MCA' end where id = 1

Answer 4

You can test for NULL in the SET clause, and use concatenation to format the string appropriately.
update student
set qualification = concat(if (qualification is not null
, concat( qualification, ',')
, '' )
, 'MBA')
where id = 1;
Here is a working SQL Fiddle (which also demonstrates behaviour with a NULL qualification).
I agree with #Abhik that this is a bad design for this specific data, and normalization is the better approach for the use case you provide However, there are other use cases where doing this sort of update would be perfectly valid so the question is worthy of a proper answer..