How to change the field type in a PostgreSQL database?

To change the field type in a PostgreSQL database, you can use the ALTER TABLE statement. Here is an example:

-- 修改字段类型为integer
ALTER TABLE table_name
ALTER COLUMN column_name SET DATA TYPE integer;

In the example above, table_name is the name of the table to be modified, column_name is the name of the field to be modified, and integer is the data type to be modified to an integer type.

Please make sure there is no risk of data loss or incorrect formatting before changing the field type. It is recommended to back up the data before modifying the field type.