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Can constraint include column value?
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General information
Forum:
Microsoft SQL Server
Category:
Other
Environment versions
SQL Server:
SQL Server 2005
Miscellaneous
Thread ID:
01481419
Message ID:
01481435
Views:
18
>>After consulting my SQL Server book I am not sure Check constraint will do the job. I don't see how I can specify to check for unique expression. Here is what I was trying to do: I want to make sure that that value "MyField + '1'" is unique for all rows in the table. Could this be done with Check constraint?
>>
>>>I'm confused. Do you need Unique constraint or Check constraint? A Table Check constraint can reference more then one column of the table to which it belongs. A Unique constraint does not support expressions, only column list.
>>>
>
>If myField is unique, MyField + '1' will be also unique. I don't see how adding some constant makes a difference in uniqueness.

That is the point; myField is NOT unique but with '1' it is.
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