CASE expr
WHEN value THEN result
[WHEN ...]
[ELSE else_result]
END | expr and value: Any type | result and else_result: Supertype of input
types. | Compares expr to value of each successive WHEN
clause and returns the first result where this comparison returns true. The
remaining WHEN clauses and else_result are not
evaluated. If the
expr = value comparison returns false or NULL for
all WHEN clauses, returns
else_result if present; if not present, returns NULL.
expr and value expressions
must be implicitly coercible to a common supertype; equality comparisons are
done on coerced values. result and else_result
expressions must be coercible to a common supertype. |
CASE
WHEN cond1 THEN result
[WHEN cond2...]
[ELSE else_result]
END | cond: BOOL | result and else_result: Supertype of input
types. | Evaluates condition cond of each successive WHEN
clause and returns the first result where the condition is true; any remaining
WHEN clauses and else_result are not evaluated. If all
conditions are false or NULL, returns
else_result if present; if not present, returns
NULL. result and else_result
expressions must be implicitly coercible to a common supertype. |
| COALESCE(expr1, ..., exprN) | Any type | Supertype of input types | Returns the value of the first non-null expression. The remaining
expressions are not evaluated. All input expressions must be implicitly
coercible to a common supertype. |
| IF(cond, true_result, else_result) | cond: BOOL | true_result and else_result: Any type. | If cond is true, returns true_result, else returns
else_result. else_result is not evaluated if
cond is true. true_result is not evaluated if
cond is false or NULL. true_result and
else_result must be coercible to a common supertype. |
| IFNULL(expr, null_result) | Any type | Any type or supertype of input types. | If expr is NULL, return null_result. Otherwise,
return expr. If expr is not NULL,
null_result is not evaluated. expr and
null_result must be implicitly coercible to a common
supertype. Synonym for COALESCE(expr, null_result). |
| NULLIF(expression, expression_to_match) | Any type T or subtype of T | Any type T or subtype of T | Returns NULL if expression = expression_to_match
is true, otherwise returns expression. expression and
expression_to_match must be implicitly coercible to a common
supertype; equality comparison is done on coerced values. |
