mysql-如何在一个sql查询中计算来自多个表的行

我有一个题目,必需从多个表中获取行计数.

譬喻：

SELECT COUNT(*) FROM table1;
SELECT COUNT(*) FROM table1 where condition;
SELECT COUNT(*) FROM table2;
SELECT COUNT(*) FROM table3 where condition;

SELECT COUNT(*) FROM table1
UNION
SELECT COUNT(*) FROM table1 where condition;
UNION
SELECT COUNT(*) FROM table2;
UNION
SELECT COUNT(*) FROM table3 where condition;

您可以添加特另外字段,以通过以下查询找到要得到的行

SELECT "COND-1" AS TITLE,COUNT(*) FROM table1
UNION
SELECT "COND-2" AS TITLE,COUNT(*) FROM table1 where condition;
UNION
SELECT "COND-3" AS TITLE,COUNT(*) FROM table2;
UNION
SELECT "COND-4" AS TITLE,COUNT(*) FROM table3 where condition;

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