Table without a identity column but this column can't have repeated values

I'm creating a table that needs to have 2 columns. The first column can't be repeated. The thing is, I will insert the value of the first column. How do I create this column? SQLSer开发者_高级运维ver 2005

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Make the first column the primary key of the table.

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Set the column as a primary key. I doesn't have to be an identity column to has a PK.

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Create it the same way you would any other column: create table sometable (column1 varchar(10), column2 varchar(20)) or whatever.

Do you mean: How can you get the database to force it to be unique? Either declare it to be the primary key, or create a unique index on the column.

Perhaps you're thinking that a primary key must be auto-generated? There's no such rule. Whether you invent the value yourself or use an autonumber feature has nothing to do with whether a field can be a primary key.

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Why not just put a unique constraint on it:

ALTER TABLE <table_name>
 ADD CONSTRAINT <constraint_name>
 UNIQUE(<column_name>)