-- 找出只在table1中但不在table2中的值

SELECT 'table1' AS source, value

FROM table1

LEFT JOIN table2 ON table1.value = table2.value

WHERE table2.value IS NULL

UNION

-- 找出只在table2中但不在table1中的值

SELECT 'table2' AS source, value

FROM table2

LEFT JOIN table1 ON table2.value = table1.value

WHERE table1.value IS NULL;

--这将只返回两个表中都存在的

SELECT '相同' AS status, t1.value

FROM table1 t1

INNER JOIN table2 t2 ON t1.value = t2.value

表相同与不同，它里除了对比行数，还有每一行的数据也有不一样呀。。你得说出对比标准