IS_FALSE Function

is_false(expr)

Description

The IS_FALSE function determines whether the value of an expression is false. This function supports boolean and string types, and can recognize various string formats that represent false.

Parameters

• expr: BOOLEAN or STRING type, the expression to evaluate.

Return Type

• Returns BOOLEAN type.
• Returns true if the expression value is false or a string representing false.
• Returns false if the expression value is true or a string representing true.
• Returns false if the expression value is NULL.

Notes

• The IS_FALSE function recognizes the following strings as false: 'f', 'false', '0', 'no'.
• The IS_FALSE function recognizes the following strings as true: 't', 'true', '1', 'yes'.
• Difference from NOT expr: is_false(NULL) returns false, while NOT NULL returns NULL.
• String matching is case-insensitive.

Examples

1. Boolean evaluation

SELECT is_false(true), is_false(false), is_false(NULL); +----------------+-----------------+-----------------+ | is_false(true) | is_false(false) | is_false(NULL) | +----------------+-----------------+-----------------+ | false | true | false | +----------------+-----------------+-----------------+

2. String evaluation (supports multiple formats)

SELECT is_false('t'), is_false('f'); +---------------+---------------+ | is_false('t') | is_false('f') | +---------------+---------------+ | false | true | +---------------+---------------+

3. Using in a WHERE clause

SELECT * FROM VALUES (true), (false), (NULL) AS t(flag) WHERE is_false(flag); +-------+ | flag | +-------+ | false | +-------+