Optimizing queries

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Hi,

I have a query that use a function and some column test to select row. It's in the form of:

SELECT * FROM TABLE
  WHERE TABLE.COLUMN1=something
     AND TABLE.COLUMN2=somethingelse
     AND function(TABLE.COLUMN3,TABLE.COLUMN4) > 0;

The result of the function does NOT depend only from the table, but also from some other tables.

Since it's long to process, I've add some output to see what's going on. I find out that the function process every row even if the row should be rejected as per the first or the second condition. Then , my question is: Is there a way to formulate a query that wont do all the check if it does not need to do it ? Meaning that, if condition1 is false then it wont check condition2 and that way the function will only be called when it's really necessary.

Thanks


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