support window function, count distinct, remove status, left and righ…

…t keywords in tsql, fix drop table if exists in mysql

fix mysql time function sqlify, support mysql insert ignore, triple s…

…ingle quote; fix pg offset

support create view, select into in mysql; fix insert bug in pg

support function dot in bigquery

fix select *, distinct bug, support session_user, window clause in bi…

…gquery

support presto style in hive

support union stmt in expr

support array index, == in hive

support exec in tsql, cross join in hive

support tablesample in pg, fix cast bug in pg, support rlike in hive