* implement Table stmt
* fmt
* add TableStmt into Statement rule, fix OFFSET rule
* support TableStmt in InsertStmt
* remove TableStmtLimit, use SelectStmtLimit instead
* support basic setoptr, need to fix a lot things
* support INTO OUTFILE
* support CREATE TABLE and CREATE VIEW
* support basic VALUES stmt
* fmt
* implement set operation for table
* add some comment
* fix the wrong implements of TABLE stmt
* fix the wrong implements of VALUES stmt
* fix SetOprNode interface
* rename the fields refer to SetOpr statement, fix some comments
* finish
* remove unused comment
* resolve conflicts
* refactor
* resolve conflicts
* fix small problems
* remove wrong use of RowStmtField