Use the SQL BIT data type to define columns, variables, and parameters value of 1, 0, or NULL.
Given their Yes/No nature, designer us the BIT type with flag and indicator columns:
Converting BIT Values
The string values TRUE and FALSE convert to BIT: TRUE is converted to 1 and FALSE to 0.
Converting any non-zero value promotes BIT to 1.
Here is SQL to query all employees receiving a salary:
To learn more about data types, check out these useful resources: