从每个表中按主键（EID，CID，FID，EnID）降序选择所有记录

Question

需要一个SQL语句，该语句从每个表中按主键ORDER BY降序选择所有记录。

这没有给出完整的说明

SELECT table_name, num_rows counter FROM user_tables;

我已经尝试过：

SELECT table_name, num_rows counter FROM user_tables;

我希望以主键降序列出所有4个表的输出ORDER BY EID，CID，FID和ENID

Answer 1

您可以为此使用联合...

SELECT EID AS ID, 'Engineers' AS TableName FROM Engineers
UNION
SELECT SID, 'Staff' FROM Staff
UNION
SELECT FID, 'Classes' FROM Classes
UNION
SELECT ENID, 'StudentEnrollments' FROM StudentEnrollments
ORDER BY 1

在这种情况下，“ ORDER BY 1”表示第一列。