constraints

raindropz · #1 (**permalink**) 04-22-11, 23:13

what is constraint? when do we need to constraint? please explain, thanks in advanced.

healdem · #2 (**permalink**) 04-23-11, 04:08

what is google?
when do we need to use it?
how do we use it?
Let me google that for you

raindropz · #3 (**permalink**) 04-24-11, 04:39

Quote:

Originally Posted by healdem

what is google?
when do we need to use it?
how do we use it?
Let me google that for you

what is the use of dbforums.com then?
when do we need to use dbforums.com?
thanks

shammat · #4 (**permalink**) 04-24-11, 05:10

Quote:

Originally Posted by raindropz

what is the use of dbforums.com then?
when do we need to use dbforums.com?

When you have a specific problem (e.g. a SQL statement or a design question) that you cannot solve by reading the manual.

raindropz · #5 (**permalink**) 04-24-11, 18:32

I don't understand the manual, isn't my question specific? thanks.

r937 · #6 (**permalink**) 04-24-11, 19:09

Quote:

Originally Posted by raindropz

isn't my question specific?

no, not really

here, let me answer it with exactly the same amount of specificity as your question --

a constraint is a restriction on the data that will be accepted by the database

when do we need to constrain? when we want the database to enforce a restriction on the data

happy now?

shammat · #7 (**permalink**) 04-24-11, 19:26

Quote:

Originally Posted by r937

when we want the database to enforce a restriction on the data

Would we ever want the database to not enforce the restriction?

raindropz · #8 (**permalink**) 04-24-11, 23:13

Quote:

Originally Posted by r937

no, not really

here, let me answer it with exactly the same amount of specificity as your question --

a constraint is a restriction on the data that will be accepted by the database

when do we need to constrain? when we want the database to enforce a restriction on the data

happy now?

can you please give examples? thanks.