Help Center/ GaussDB/ M-Compatibility Developer Guide(Distributed)/ SQL Reference/ Expressions/ Simple Expressions
Updated on 2025-10-23 GMT+08:00
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Simple Expressions

Logical Expressions

Logical Operators lists the operators and calculation rules of logical expressions.

Comparison Expressions

Comparison Functions and Comparison Operators lists the common comparison operators.

In addition to comparison operators, you can also use the following sentence structures:

BETWEEN operator 
a  BETWEEN  x  AND  y

Generally, it is equivalent to a ≥ x AND a ≤ y.

a  NOT BETWEEN  x  AND y

Generally, it is equivalent to a < x OR a > y.

  • During conversion, the BETWEEN operator first determines the comparison type for a and x, and then determines the final comparison type based on the comparison type for a and x as well as y. Therefore, the result is not equivalent to that of a >= x AND a <= y in complex scenarios.
  • In a BETWEEN x AND y, x and y cannot use expressions, for example, 1 < 1.

Example

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m_db=# SELECT 2 BETWEEN 1 AND 3 AS RESULT;
 result 
----------
 t
(1 row)

m_db=# SELECT 2 >= 1 AND 2 <= 3 AS RESULT;
 result 
----------
 t
(1 row)

m_db=# SELECT 2 NOT BETWEEN 1 AND 3 AS RESULT;
 result 
----------
 f
(1 row)

m_db=# SELECT 2 < 1 OR 2 > 3 AS RESULT;
 result 
----------
 f
(1 row)

m_db=# SELECT '2' between 'a' AND 3.0 AS RESULT;
WARNING:  Truncated incorrect double value: 'a'
CONTEXT:  referenced column: RESULT
 result
----------
 t
(1 row)

m_db=# SELECT '2' >= 'a' AND '2' <= 3.0 AS RESULT;
 result
----------
 f
(1 row)
Parent topic: Expressions