Sql-server – Column definition for a SQL Server equivalent to Access BOOLEAN type

ddlms accesssql server

The BOOLEAN datatype in Access (ie, Jet/ACE) returns a -1 for True and 0 for False; the field is always required (i.e., it cannot be set to NULL). The SQL Server BIT type returns 1 for True and 0 for False and also allows NULLs.

I'm looking for a T-SQL column definition using a combination of smallint, check constraints, and NOT NULL to replicate the functionality of the Jet/ACE BOOLEAN datatype. In other words, the column would only accept the values 0 and -1.

Best Answer

To address your concerns about BIT:

  1. You can set your BIT column to NOT NULL.
  2. You can use -1 when setting a BIT column to "true".
  3. You can create a view that translates to -1, but +1 should be fine anyway unless your application explicitly checks for the numeric -1 (anything but zero should yield true in your client language).
CREATE TABLE dbo.foo(bar BIT NOT NULL, blat BIT NOT NULL);

INSERT dbo.foo SELECT -1, 0;

SELECT bar, blat, -CONVERT(SMALLINT, bar), -CONVERT(SMALLINT, blat) FROM dbo.foo;

Results:

bar   blat   
----  ----  ----  ----
1     0     -1    0

The nice thing about BIT over TINYINT/SMALLINT is that if you have between 1-8 BIT columns, they can fit into a single byte.

In all of these cases, you still aren't going to be able to say 

WHERE NOT BooleanColumn
-- or
WHERE !BooleanColumn

You will still have to say

WHERE BooleanColumn = 0
Related Question