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field not allowing duplicates

Author

Topic

esthera
Master Smack Fu Yak Hacker

1410 Posts

Posted - 2007-03-05 : 06:29:59

in sql management express how do i indicate a field that does not allow duplicates?

harsh_athalye
Master Smack Fu Yak Hacker

5581 Posts

Posted - 2007-03-05 : 06:51:26

Make field non-null and add UNIQUE constraint on the field.

Harsh Athalye
India.
"The IMPOSSIBLE is often UNTRIED"

esthera
Master Smack Fu Yak Hacker

1410 Posts

Posted - 2007-03-05 : 07:01:29

how do i do this in management express?

esthera
Master Smack Fu Yak Hacker

1410 Posts

Posted - 2007-03-08 : 02:11:28

can you tell me the syntax to do this -- to change the field to have a unique constraint

harsh_athalye
Master Smack Fu Yak Hacker

5581 Posts

Posted - 2007-03-08 : 02:18:37

[code]-- to make field Non-Nullable
alter table <table-name>
alter column <column-name> <data-type> not null
GO

-- to add unique constraint
alter table <table-name>
add constraint <constraint-name> unique(<column-name>)
GO[/code]

Harsh Athalye
India.
"The IMPOSSIBLE is often UNTRIED"

esthera
Master Smack Fu Yak Hacker

1410 Posts

Posted - 2007-03-08 : 02:25:50

what should be the constraint name or does it not matter?

harsh_athalye
Master Smack Fu Yak Hacker

5581 Posts

Posted - 2007-03-08 : 02:30:20

You can give any descriptive name or it may depend upon your company's naming standards.

Harsh Athalye
India.
"The IMPOSSIBLE is often UNTRIED"

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