why is that u can insert more than 1 NULL value to a filed declared as unique in oracle and ms access and not in others ( ms sql , sybase...)......which one is right? allowing NULL values to be inserted or not?
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why is that u can insert more than 1 NULL value to a filed declared as unique in oracle and ms access and not in others ( ms sql , sybase...)......which one is right? allowing NULL values to be inserted or not?
unique means no duplication, and since you said
insert nulls, i assumed you tried to insert many
nulls which it should error because they are not
unique.
For example:
You have a table which has 1000 rows and the 5th
column contains nulls, if you try to create a unique
index on that field, it should not let you do it because
it is not unique ( all nulls or have similar values).