1 SET
2+ ,
2 variable  = 
2.1 expression
2.1 NULL
2 (
2.1+ ,
2.1 variable
2.2 )  =  (
2.2.1.0.0+ ,
2.2.1.0.0 expression
2.2.1.0.0 NULL
2.2.1.0 row-fullselect
2.2.2 )