Is there a Boolean data type in Microsoft SQL Server like there is in MySQL? [duplicate]

You could use the BIT datatype to represent boolean data. A BIT field's value is either 1, 0, or null.

You may want to use the BIT data type, probably setting is as NOT NULL:

Quoting the MSDN article:

bit (Transact-SQL)

An integer data type that can take a value of 1, 0, or NULL.

The SQL Server Database Engine optimizes storage of bit columns. If there are 8 or less bit columns in a table, the columns are stored as 1 byte. If there are from 9 up to 16 bit columns, the columns are stored as 2 bytes, and so on.

The string values TRUE and FALSE can be converted to bit values: TRUE is converted to 1 and FALSE is converted to 0.

You are looking for a bit. It stores 1 or 0 (or NULL).

Alternatively, you could use the strings 'true' and 'false' in place of 1 or 0, like so-

declare @b1 bit = 'false'print @b1                    --prints 0declare @b2 bit = 'true'print @b2                    --prints 1

Also, any non 0 value (either positive or negative) evaluates to (or converts to in some cases) a 1.

declare @i int = -42print cast(@i as bit)    --will print 1, because @i is not 0

Note that SQL Server uses three valued logic (true, false, and NULL), since NULL is a possible value of the bit data type. Here are the relevant truth tables -

More information on three valued logic-

Example of three valued logic in SQL Server

http://www.firstsql.com/idefend3.htm

https://www.simple-talk.com/sql/learn-sql-server/sql-and-the-snare-of-three-valued-logic/