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Oracle DB Trigger

Posted on 2013-11-18
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I am receiving data which is too big for one of the database fields. I created a trigger to truncate the data to the correct size:
However, when the field is too big, the error seems to appear before the trigger is invoked. If the field is the correct length, the trigger is clearly executed.

Is this the expected behavior? Am I doing something wrong?
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Question by:TomDarby
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3 Comments
 
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sdstuber earned 500 total points
ID: 39657184
check constraints  like nullability or upper/lower  and foreign key constraints are applied after triggers fire.

basic structural limits (data type, data size) are applied before triggers fire - by necessity.  
Your trigger couldn't have a ":new.value"  of varchar2(20) with a 50 character string in it.

You will have to correct the length before putting the value in,  or make the column definition bigger.
You could then apply a check constraint to ensure the trigger-modified value was of the appropriate shorter length.
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Expert Comment

by:slightwv (䄆 Netminder)
ID: 39657194
I believe length and syntax restrictions are checked at the time the statement is parsed which is before it is executed so the trigger isn't going to work.

As a DBA, the question I have is why it would be acceptable to truncate data and therefore lose it.

If someone passes you data, they sort of expect it to be stored.  Don't they?

Can you not change the table to account for the maximum length you can be sent?

If not, maybe load the data into a staging table for processing before adding it into the main table.
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Author Closing Comment

by:TomDarby
ID: 39657212
The routine is being passed a 12 position postal code and it only needs 9 so I was hoping to truncate it. I guess that will not work.
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