Hi guys, i want to optimize fields with ENUM() in item comparation the point is: SELECT COUNT(*) FROM table WHERE enum_field!='x' column 'enum_field' is ENUM('x,'y','z') NOT NULL DEFAULT 'x' i want to rewrite the query in a way that we can execute it with index: SELECT COUNT(*)FROM table WHERE enum_field IN ('y','z','') the "" is not allowed values ('a' for example) the feature is 'easy' to understand but i don't know where to implement it will read possible values of enum fields, and rewrite "!=","<","<=",">=",">" operators to IN operator with fields that match the condition of the primary operator some think like: column "operator" const value if(operator in ('!=','<','<=','>=','>' AND column is ENUM){ get all possible values from column copy all values to a return variable execute the "operator" in all values with const values if operator return false remove the value from the return variable change the "operator" and "const value" to : "IN" and return variable comma separated }else{ no optimization leave operation as it is } example: column = enum('x','y','z'), operator = ">" const value = "3" if(column is ENUM and operator = ">"){ possible values => "x","y","z","" (check that "" is used when insert into, value = "a" for example) return variable = "x","y","z", "" for each value.... "x" > "3" ? yes, ASCII 120 > ASCII 51 -> do nothing "y" > "3" ? yes, ASCII 121 > ASCII 51 -> do nothing "z" > "3" ? yes, ASCII 122 > ASCII 51 -> do nothing "" > "3" ? no, "" < ASCII 51 -> remove the value "" from return variable end for now the return variable is : "x","y","z" the "" was removed rewrite the operator to: "column IN ('x','y','z')" } ----------------------- this will optimize a lot: using != in a big table (446577 rows) result = Using where, 446577 rows, type= ALL using IN() in a big table: result = Using where, 28 rows, key = index, type = range in other words, a lot of optimization with ENUM fields, since they are a pseudo "index" of what we can found in the column =) thank guys any help is wellcome to make a patch -- Roberto Spadim SPAEmpresarial