1-- 1. Create new table without NOT NULL on campaign 2CREATE TABLE campaigns_new 3( 4 session TEXT PRIMARY KEY REFERENCES sessions (session) ON DELETE CASCADE ON UPDATE CASCADE, 5 campaign TEXT, 6 source TEXT, 7 medium TEXT 8); 9 10-- 2. Copy data 11INSERT INTO campaigns_new (session, campaign, source, medium) 12SELECT session, campaign, source, medium FROM campaigns; 13 14-- 3. Drop old table 15DROP TABLE campaigns; 16 17-- 4. Rename new table 18ALTER TABLE campaigns_new RENAME TO campaigns; 19 20-- 5. Recreate indexes 21CREATE INDEX idx_campaigns_campaign ON campaigns (campaign); 22CREATE INDEX idx_campaigns_source ON campaigns (source); 23CREATE INDEX idx_campaigns_medium ON campaigns (medium); 24