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Cytat
Changing the data type of a column can be done easily in 8.0 and later with ALTER TABLE ALTER COLUMN TYPE
In earlier releases, do this:
BEGIN;
ALTER TABLE tab ADD COLUMN new_col new_data_type;
UPDATE tab SET new_col = CAST(old_col AS new_data_type);
ALTER TABLE tab DROP COLUMN old_col;
COMMIT;
pozostaje na piechotke napisac sobie procedurke....