Data duplication using mysql query

Question

I wanted a guidance for one problem . Suppose i have one table alphabets (alpha, id).
In column alpha having value a-z and in column id all values are 1.

a  1
b  1
.  .
.  .
z  1

Now i want a database query to insert data like a-z but with id=2 .

Can anybody help me out .

Toby Allen · Accepted Answer · 2010-07-18 20:21:46Z

6

INSERT INTO alphabets (alpha, id)
SELECT alpha, 2
  FROM alphabets a
 WHERE id = 1
   AND NOT EXISTS (
        SELECT * FROM alphabets
         WHERE alpha = a.alpha
           AND id = 2
       )

Note that the WHERE clause makes this query idempotent, i.e., it won't duplicate the id=2 rows if you run it twice.

edited Jul 18, 2010 at 20:21

Toby Allen

11.3k12 gold badges80 silver badges132 bronze badges

answered Jul 17, 2010 at 12:19

Marcelo Cantos

187k40 gold badges338 silver badges366 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Data duplication using mysql query

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related