...
->join(
       "m_region_new c",
       "a.column1= c.column2", "LEFT")
...

...
->join(
       "m_region_new c",
       "a.column1= c.column2::integer", "LEFT")
...

... LEFT JOIN "m_region_new" "c"."column2::integer" ...

... LEFT JOIN "m_region_new" "c"."column2"::integer ...

ERROR: column c.column2"::integer does not exist LINE 7: ...