计算数据库表中的TOTAL行数[重复]

I would like to know how to Count the TOTAL number of rows in the tables of a database. For example, I have 3 tables in a database called:

Table 1: 5 rows

Table 2: 4 rows

Table 3: 3 rows

So the output should be: 12 rows.

I know how to count rows in a specific table. Is there something to loop here?

Thanks.

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SELECT sum(cnt) AS overall_cnt
FROM (
    SELECT count(*) AS cnt FROM table1
    UNION ALL
    SELECT count(*) AS cnt FROM table2
    UNION ALL
    SELECT count(*) AS cnt FROM table3
) AS foo

SELECT sum(TABLE_ROWS)
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME IN ('table1', 'table2', 'table3');

SELECT SUM(TABLE_ROWS)
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'db_name';