Does SQL Server 2005 have an equivalent to MySql&#

问题:

I'm working on a project and I want to store some easily enumerated information in a table. MySql's enum data type does exactly what I want: http://dev.mysql.com/doc/refman/5.0/en/enum.html . Is there an equivalent in SQL Server 2005?

I know I could store the possible values in a type table with a key, but I'd rather not have to link back to it for descriptions. Our database standards don't allow us to link on non-integer or uniqueidentifier fields, so storing the possible keys as characters is out as well.

回答1:

Does this work for you?

From http://blechie.com/wtilton/archive/2007/08/24/303.aspx

Create table...

MySQL:

ColumnName ENUM('upload', 'open', 'close', 'delete', 'edit', 'add')
   DEFAULT 'open'

SQL Server:

ColumnName varchar(10) 
   CHECK(ColumnName IN ('upload', 'open', 'close', 'delete', 'edit', 'add')) 
   DEFAULT 'open'

回答2:

One characteristic of MySQL's ENUM data type is that it stores only a numeric index into the list of values, not the string itself, on each row. So it's usually more storage-efficient. Also the default behavior when you sort by an ENUM column is to sort by the numeric index, therefore by the order of elements in the ENUM.

Nikki9696 suggests using a VARCHAR column with a CHECK constraint. This satisfies the restriction of values to a certain short list of permitted values, but it doesn't simulate the storage efficiency or the special sort order.

One way to get both behaviors is to declare the column as an integer foreign key into a lookup table, in which you store each permitted string.