Documentation Home
MySQL 5.7 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 35.1Mb
PDF (A4) - 35.2Mb
Man Pages (TGZ) - 256.4Kb
Man Pages (Zip) - 361.2Kb
Info (Gzip) - 3.4Mb
Info (Zip) - 3.4Mb
Excerpts from this Manual

MySQL 5.7 Reference Manual  / ...  / Functions and Operators  / Operators  /  Logical Operators

12.4.3 Logical Operators

Table 12.5 Logical Operators

NameDescription
AND,&& Logical AND
NOT,! Negates value
OR,|| Logical OR
XOR Logical XOR

In SQL, all logical operators evaluate toTRUE,FALSE, orNULL (UNKNOWN). In MySQL, these are implemented as 1 (TRUE), 0 (FALSE), andNULL. Most of this is common to different SQL database servers, although some servers may return any nonzero value forTRUE.

MySQL evaluates any nonzero, non-NULL value toTRUE. For example, the following statements all assess toTRUE:

mysql> SELECT 10 IS TRUE;-> 1mysql> SELECT -10 IS TRUE;-> 1mysql> SELECT 'string' IS NOT NULL;-> 1

  • NOT,!

    Logical NOT. Evaluates to1 if the operand is0, to0 if the operand is nonzero, andNOT NULL returnsNULL.

    mysql> SELECT NOT 10;        -> 0mysql> SELECT NOT 0;        -> 1mysql> SELECT NOT NULL;        -> NULLmysql> SELECT ! (1+1);        -> 0mysql> SELECT ! 1+1;        -> 1

    The last example produces1 because the expression evaluates the same way as(!1)+1.

  • AND,&&

    Logical AND. Evaluates to1 if all operands are nonzero and notNULL, to0 if one or more operands are0, otherwiseNULL is returned.

    mysql> SELECT 1 AND 1;        -> 1mysql> SELECT 1 AND 0;        -> 0mysql> SELECT 1 AND NULL;        -> NULLmysql> SELECT 0 AND NULL;        -> 0mysql> SELECT NULL AND 0;        -> 0

  • OR,||

    Logical OR. When both operands are non-NULL, the result is1 if any operand is nonzero, and0 otherwise. With aNULL operand, the result is1 if the other operand is nonzero, andNULL otherwise. If both operands areNULL, the result isNULL.

    mysql> SELECT 1 OR 1;        -> 1mysql> SELECT 1 OR 0;        -> 1mysql> SELECT 0 OR 0;        -> 0mysql> SELECT 0 OR NULL;        -> NULLmysql> SELECT 1 OR NULL;        -> 1
    Note

    If thePIPES_AS_CONCAT SQL mode is enabled,|| signifies the SQL-standard string concatenation operator (likeCONCAT()).

  • XOR

    Logical XOR. ReturnsNULL if either operand isNULL. For non-NULL operands, evaluates to1 if an odd number of operands is nonzero, otherwise0 is returned.

    mysql> SELECT 1 XOR 1;        -> 0mysql> SELECT 1 XOR 0;        -> 1mysql> SELECT 1 XOR NULL;        -> NULLmysql> SELECT 1 XOR 1 XOR 1;        -> 1

    a XOR b is mathematically equal to(a AND (NOT b)) OR ((NOT a) and b).