| why constraints [message #80305] |
Thu, 05 September 2002 01:08  |
yram
Messages: 75
Registered: February 2001
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Member |
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hi
We are using costraint in the table level.
though we have the constraints in almost every table then we use the front end like (D2K,VB) to validate the columns which are in the table,
my question is that what is the use of the constraints in the table level then.
do explain in details abt this
regards
yram
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| Re: why constraints [message #80306 is a reply to message #80305] |
Thu, 05 September 2002 02:01  |
N
Messages: 26
Registered: April 2002
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Junior Member |
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hi yram,
Constraints are enforced to maintain the referential integrity of the data in the dbase. Here let me explain with a very simple but, i hope, effective example.
Eg. Here are all my cutomers for ORACLOTHING LTD.
CUST A
CUST B
CUST C.
Yesterday we received an order from a person called CUSTOMER Z. He wants 100 Ora shirts. We would like to get his order out right away because its worth alot of money. We cannot invoice him at this stage because he does not exist as a customer yet. (We have to create his record first before we can invoice him).
AT a very basic level you can relate the concept of constraints/ref integrity to this:
"It has to be (stored) in this table first before it can be (stored) in that table.
n.
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