


        the SQL Where clause is a Filter, it restricts the rows returned
        by the command
        
        in the Where clause I can code these operations:
        
        Comparison Tests:
        column = data <- an exact match
        column > data <- where the column contains a value Greater Than the data
        column >= data <- where the column contains a value Greater Than or Equal to the data
        column < data <- where the column contains a value less Than the data
        column <= data <- where the column contains a value Less Than or Equal to the data
        column <> data <- where the column contains a value Not Equal (I can also code !=)
        
        Range Test:
        column BETWEEN value1 AND value2 <- all rows w/ a value in this range, it include the end values
        
        
        Membership Test:
        column IN (value1, value2, value3) <- all rows w/ a value in the list
        column NOT IN (value1, value2, value3) <- all rows w/ a value outside the list
        
        Pattern Matching Test:
        column LIKE 'A%' <- all rows w/ the data startign w/ 'A'
        column LIKE 'A_s%' <- all rows w/ the data starting w/ 'A', the 3rd char is 's'
                                followed by zero or more chars
                                
        Null Test:
        column IS NULL <- all rows with a 'null' in that columns, note this will NOT match
                           spaces in that column
        column IS NOT NULL <- all rows w/ a non-null value in that column
        
        
        I can combine these tests with a OR (either side is true, the row is returned)
        and AND (both side must be true for the row to be returned)
        or a NOT (reverse the true/false value) These are compound where clauses,
        I really should use ( )
        
        
        
        
        
