Entering the following command into a PostgreSQL interactive terminal results in an error:
ALTER TABLE tbl_name ALTER COLUMN col_name varchar (11);
What is the correct command to alter the data type of a column?
Try the code given below:
ALTER TABLE tbl_name ALTER COLUMN col_name TYPE varchar (11);
For more information, refer to this documentation: http://www.postgresql.org/docs/current/interactive/sql-altertable.html