要在一組固定的表中搜索,您可以使用 UNION
子句組合各個(gè)查詢,然后添加一個(gè)硬編碼的字符串來(lái)標(biāo)識(shí)來(lái)源:
SELECT packaging_id AS product_id, 'packaging' AS table_name FROM packaging WHERE name = 'Cardboard box' UNION ALL SELECT stationery_id, 'stationery' FROM stationery WHERE description = 'Cardboard box' UNION ALL SELECT sales_id, 'sales' FROM sales WHERE offer = 'Cardboard box'
您需要確保結(jié)果集中每個(gè)列具有相同的數(shù)據(jù)類型,并且您可以使用第一個(gè)語(yǔ)句為結(jié)果集設(shè)置一個(gè)規(guī)范化的列名。