Insert statement that checks for duplicate before insert

Question

I need to make a insert but only if similar record don\'t exists
for example:

INSERT INTO requests (\'user_id\',\'subject\',\'text\',\'time\') V

Answer 1

First, you can do the update. If the record doesn't exist, nothing will happen...

UPDATE
  requests
SET
  user_id = 56,
  time = 6516516
WHERE
  subject = 'test'
  AND text = 'test 1234'

Then you can use SELECT instead of VALUES in the INSERT. If the record already exists, nothing will be inserted...

INSERT INTO
  requests (
    user_id,
    subject,
    text,
    time
  )
SELECT
  56,
  'test',
  'test 1234',
  6516516
WHERE
  NOT EXISTS (SELECT * FROM requests WHERE subject = 'test' AND text = 'test 1234')

Answer 2

INSERT INTO requests ('user_id','subject','text','time') 
VALUES (56,'test','test 1234',6516516)
ON DUPLICATE KEY UPDATE time = VALUES(time), user_id = VALUES(user_id)

Have the relevant columns set to index UNIQUE.

This will insert a row, but if subject or text (or both) already exist, you instead update the existing row with given time and user_id

Answer 3

Replace your query from

INSERT INTO requests ('user_id','subject','text','time') VALUES (56,'test','test 1234',6516516)

To,

REPLACE INTO requests ('user_id','subject','text','time') VALUES (56,'test','test 1234',6516516)

This will add a small delay to the execution, but it is more efficient than any other method

Answer 4

You can use IGNORE command

For example, use like this

INSERT IGNORE INTO requests ('user_id','subject','text','time') VALUES (56,'test','test 1234',6516516)

instead of,

INSERT INTO requests ('user_id','subject','text','time') VALUES (56,'test','test 1234',6516516)

Answer 5

IF NOT EXISTS (SELECT user_id, text from users where user_id = @user_id AND text = @text) BEGIN
   INSERT INTO users ....
ELSE
   UPDATE users SET xyz=uvw where user_id = @user_id AND text = @text
END

Answer 6

Look at the REPLACE mysql statement?