How to fix Cannot change data type of view column in PostgreSQL

-- View the current view definition
SELECT pg_get_viewdef('your_view_name'::regclass, true);

-- Check the underlying table structure
DESC your_table_name;
-- or
SELECT column_name, data_type FROM information_schema.columns 
WHERE table_name = 'your_table_name' AND table_schema = 'public';

-- Drop the view (fails if other views depend on it)
DROP VIEW your_view_name;

-- Drop the view and dependent views
DROP VIEW your_view_name CASCADE;

-- Example: View was returning varchar, table now returns text
-- OLD (fails):
CREATE OR REPLACE VIEW user_summary AS
SELECT 
  id,
  name::varchar,  -- was varchar, now needs to be text
  email::varchar
FROM users;

-- NEW (correct):
CREATE VIEW user_summary AS
SELECT 
  id,
  name,  -- matches table column type directly
  email
FROM users;

-- Dependent view that referenced your_view_name
CREATE VIEW user_details AS
SELECT 
  us.id,
  us.name,
  us.email,
  COUNT(o.id) as order_count
FROM user_summary us
LEFT JOIN orders o ON us.id = o.user_id
GROUP BY us.id, us.name, us.email;

-- Query the view
SELECT * FROM user_summary LIMIT 5;

-- Check column types in the view
SELECT column_name, udt_name FROM information_schema.columns
WHERE table_name = 'user_summary' AND table_schema = 'public';

-- Verify dependent views
SELECT * FROM user_details LIMIT 5;