https://www.sqlite.org/lang_createtable.html#constraints
Procs
proc createColumnString(column: Column): string {....raises: [DbError, KeyError], tags: [], forbids: [].}
proc createForeignString(column: Column): string {....raises: [KeyError], tags: [], forbids: [].}
proc createIndexString(table: Table; column: Column): string {....raises: [], tags: [], forbids: [].}