Andrus wrote:
>> I have a strange problem with the following condition in a SELECT:
>> AND (("TableData" = "inDate") OR ("inDate" IS NULL))
>>
>> it works perfectly when the input date in the function (inDate) matchs
>> a date in the table, but it does not work when the parameter inDate is
>> NULL.
>> I recall the function with pgadmin writing NULL as paramater.
>> It seems that ("inDate" IS NULL) never returns true, even when the
>> parameter is null...
>> What's wrong?
> 
> Order is wrong, change it to
>> AND (("inDate" IS NULL) OR ("TableData" = "inDate") )
> 
> PostgreSQL OR is not commutative if left operand evaluates to NULL.

Seems to work here:

select (true or null) as a, (null or true) as b, (null or false) as c,
(false or null) as d;
 a | b | c | d
---+---+---+---
 t | t |   |
(1 row)


-- 
  Richard Huxton
  Archonet Ltd

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