SQL Server - boolean literal?

sql sql-server boolean literals
dpp picture dpp · Aug 24, 2011 · Viewed 192.5k times · Source

How to write literal boolean value in SQL Server? See sample use:

select * from SomeTable where PSEUDO_TRUE

another sample:

if PSEUDO_TRUE
begin
  select 'Hello, SQL!'
end

Note: The query above has nothing to do with how I'm going to use it. It is just to test the literal boolean.

Answer

Damien_The_Unbeliever picture Damien_The_Unbeliever · Aug 24, 2011

SQL Server doesn't have a boolean data type. As @Mikael has indicated, the closest approximation is the bit. But that is a numeric type, not a boolean type. In addition, it only supports 2 values - 0 or 1 (and one non-value, NULL).

SQL (standard SQL, as well as T-SQL dialect) describes a Three valued logic. The boolean type for SQL should support 3 values - TRUE, FALSE and UNKNOWN (and also, the non-value NULL). So bit isn't actually a good match here.

Given that SQL Server has no support for the data type, we should not expect to be able to write literals of that "type".

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