php mySQL check for unique value needed on Unique col?

Question

is it necessary to check for Unique Value before insert it in to a database? if the unique_col is predefine to be Unique Keys.

for example

 SELECT unique_col FROM table WHERE unique_col != unique_val 
 INSERT INTO table (unique_col) VALUE(:unique_value)

Gordon Linoff · Accepted Answer · 2015-09-26 16:09:57Z

1

Is it necessary to check? That depends how you are handling the error.

In general, the database is going to do the check anyway, so an additional check on your part is redundant. If you do the check, another thread might insert the same value between your check and the insert, so you can still get an error (this is called a race condition).

So, don't do the check, but do check for the error.

answered Sep 26, 2015 at 16:09

Gordon Linoff

1.3m62 gold badges706 silver badges857 bronze badges

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

Collectives™ on Stack Overflow

php mySQL check for unique value needed on Unique col?

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