fix on clause bug in pg, support row in windows function in mysql, ca…

…st with expr in pg

fix many bugs, support window in pg and mysql

move unay expr after or expr

support function expression as table in pg, support convert and cast …

…in mysql

support where clause wrapped by parentheses, fix schema prefix bug in pg

support schema prefix in pg, sqlify replace into ast, fix string cons…

…tants bug in pg

fix case when with parentheses, fix reserved keywords in mysql, suppo…

…rt string constant in pg

support similar to in pg, refactor on update current_timestamp in mysql

support case when with multiple condition, fix create table with row_…

…format, support alter table rename column in mysql

support div as division, add create type definition