How to convert column type from varchar to date in PostgreSQL?

Question

I have varchar data type column and date data type column.

I have to update varchar column data into date column

Answer 1

UPDATE tableName SET dateColumn=to_date(varcharColumn, 'DD MM YYYY')

Assuming you are saving "07 04 2010"

You can find further examples and explanation in the documentation:

http://www.postgresql.org/docs/current/interactive/functions-formatting.html

Answer 2

syntax for typecasting:

alter table table_name alter column_name 
   type converting_data_type using(column_name::converting_data_type)

converting from varchar to date

alter table table_name 
  alter column_name type date using(column_name::date)

Answer 3

ALTER TABLE <tablename> ALTER COLUMN <columnname> TYPE DATE 
using to_date(<columnname>, 'YYYY-MM-DD');

Answer 4

to_date('05 Dec 2000', 'DD Mon YYYY')