Are there reasons for not storing boolean values in SQL as bit data types?

Question

Are there reasons for not storing boolean values in SQL as bit data types without NULL? I see them often stored as integers without constraints to limit values to 0 and 1,

Answer 1

I'd always stick with the smallest data type I can to store this.

• SQLServer: BIT
• Oracle: NUMBER(1) (or BOOLEAN in PL/SQL)
• MySQL: TINYINT (iirc BOOLEAN maps to this automatically)

Edit: Oracle's BOOLEAN is PL/SQL only, not table definition. Updated answer to reflect this.