support div as division, add create type definition

fix bigquery issue, support pg aggr fun

support create index, alter change column in mysql, serial datatype i…

…n pg

fix parentheses in where clause

support json funcion in from, || in where for sqlite

fix offset and ordinal in bigquery

support group_concat in all db

support group_concat in mysql

create table mysql with column check, add boolean type

support enum, and datetime fsp