Newbie - Help with Constraints

Dear all,
I am new to SQL Server (using the express edition.) I need to set up a
contraint that checks values from one column in three tables against
one column's value in a pending insertion. If the value that is
attempting to be inserted equals a value from either of the three
tables, the insertion should fail (throw a SQL exception').
Essentially this constraint should operate just like a "no duplicates"
constraint would operate if all the data was in a single column in a
single table and a client attempted to add a duplicate value.
Any advice is appreciated.
Thanks,
JohnnyJohnny,
You could embed the INSERT in a stored procedure and perform the table
checks (SELECTs) prior to the INSERT. Or you could create an INSERT trigger
that would ROLLBACK if the value existed in one of the tables. The former
would be better for performance.
HTH
Jerry
"Johnny Meredith" <jmeredith@.gmail.com> wrote in message
news:1148501225.921395.254460@.y43g2000cwc.googlegroups.com...
> Dear all,
> I am new to SQL Server (using the express edition.) I need to set up a
> contraint that checks values from one column in three tables against
> one column's value in a pending insertion. If the value that is
> attempting to be inserted equals a value from either of the three
> tables, the insertion should fail (throw a SQL exception').
> Essentially this constraint should operate just like a "no duplicates"
> constraint would operate if all the data was in a single column in a
> single table and a client attempted to add a duplicate value.
> Any advice is appreciated.
> Thanks,
> Johnny
>|||If I put this in a stored procedure, how could I ensure that the stored
procedure is called every time an insert statement is executed against
3 different tables? Is this a situation where a trigger is the only
choice?
Thanks,
Johnny|||Johnny,
Put the INSERT statement within the stored procedure and call the proc to
perform the INSERT.
HTH
Jerry
"Johnny Meredith" <jmeredith@.gmail.com> wrote in message
news:1148527276.838343.179960@.i39g2000cwa.googlegroups.com...
> If I put this in a stored procedure, how could I ensure that the stored
> procedure is called every time an insert statement is executed against
> 3 different tables? Is this a situation where a trigger is the only
> choice?
> Thanks,
> Johnny
>