基于上面@Nathan的回答，但不需要“删除最终的联合”，并带有对输出进行排序的选项，我使用以下SQL。它生成另一个SQL语句，然后运行:

select CONCAT( 'select * from (\n', group_concat( single_select SEPARATOR ' UNION\n'), '\n ) Q order by Q.exact_row_count desc') as sql_query
from (
    SELECT CONCAT(
        'SELECT "', 
        table_name, 
        '" AS table_name, COUNT(1) AS exact_row_count
        FROM `', 
        table_schema,
        '`.`',
        table_name, 
        '`'
    ) as single_select
    FROM INFORMATION_SCHEMA.TABLES 
    WHERE table_schema = 'YOUR_SCHEMA_NAME'
      and table_type = 'BASE TABLE'
) Q 

您确实需要一个足够大的group_concat_max_len服务器变量的值，但是从MariaDb 10.2.4开始，它应该默认为1M。

对于这个估算问题，有一点hack/workaround。

Auto_Increment -由于某些原因，如果您在表上设置了自动增量，则此函数将为数据库返回更准确的行数。

在探索为什么显示表信息与实际数据不匹配时发现了这一点。

SELECT
table_schema 'Database',
SUM(data_length + index_length) AS 'DBSize',
SUM(TABLE_ROWS) AS DBRows,
SUM(AUTO_INCREMENT) AS DBAutoIncCount
FROM information_schema.tables
GROUP BY table_schema;


+--------------------+-----------+---------+----------------+
| Database           | DBSize    | DBRows  | DBAutoIncCount |
+--------------------+-----------+---------+----------------+
| Core               |  35241984 |   76057 |           8341 |
| information_schema |    163840 |    NULL |           NULL |
| jspServ            |     49152 |      11 |            856 |
| mysql              |   7069265 |   30023 |              1 |
| net_snmp           |  47415296 |   95123 |            324 |
| performance_schema |         0 | 1395326 |           NULL |
| sys                |     16384 |       6 |           NULL |
| WebCal             |    655360 |    2809 |           NULL |
| WxObs              | 494256128 |  530533 |        3066752 |
+--------------------+-----------+---------+----------------+
9 rows in set (0.40 sec)

然后，您可以轻松地使用PHP或其他工具返回2个数据列的最大值，以给出行数的“最佳估计”。

即。

SELECT
table_schema 'Database',
SUM(data_length + index_length) AS 'DBSize',
GREATEST(SUM(TABLE_ROWS), SUM(AUTO_INCREMENT)) AS DBRows
FROM information_schema.tables
GROUP BY table_schema;

Auto Increment将始终是+1 *(表数)行，但即使有4000个表和300万行，这也是99.9%的准确性。比估计的行数好多了。

这样做的好处是，performance_schema中返回的行计数也会被擦除，因为greatest对null无效。但是，如果没有带有自动递增功能的表，这可能是个问题。

下面的查询生成一个(另一个)查询，该查询将从information_schema.tables中列出的每个模式中获取每个表的count(*)值。这里显示的查询的整个结果——所有行放在一起——包含一个以分号结尾的有效SQL语句——没有悬空的“联合”。在下面的查询中使用联合来避免悬空联合。

select concat('select "', table_schema, '.', table_name, '" as `schema.table`,
                          count(*)
                 from ', table_schema, '.', table_name, ' union ') as 'Query Row'
  from information_schema.tables
 union
 select '(select null, null limit 0);';

这个存储过程列出表，统计记录，并在最后生成记录的总数。

添加此过程后运行:

CALL `COUNT_ALL_RECORDS_BY_TABLE` ();

-

过程:

DELIMITER $$

CREATE DEFINER=`root`@`127.0.0.1` PROCEDURE `COUNT_ALL_RECORDS_BY_TABLE`()
BEGIN
DECLARE done INT DEFAULT 0;
DECLARE TNAME CHAR(255);

DECLARE table_names CURSOR for 
    SELECT table_name FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = DATABASE();

DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

OPEN table_names;   

DROP TABLE IF EXISTS TCOUNTS;
CREATE TEMPORARY TABLE TCOUNTS 
  (
    TABLE_NAME CHAR(255),
    RECORD_COUNT INT
  ) ENGINE = MEMORY; 


WHILE done = 0 DO

  FETCH NEXT FROM table_names INTO TNAME;

   IF done = 0 THEN
    SET @SQL_TXT = CONCAT("INSERT INTO TCOUNTS(SELECT '" , TNAME  , "' AS TABLE_NAME, COUNT(*) AS RECORD_COUNT FROM ", TNAME, ")");

    PREPARE stmt_name FROM @SQL_TXT;
    EXECUTE stmt_name;
    DEALLOCATE PREPARE stmt_name;  
  END IF;

END WHILE;

CLOSE table_names;

SELECT * FROM TCOUNTS;

SELECT SUM(RECORD_COUNT) AS TOTAL_DATABASE_RECORD_CT FROM TCOUNTS;

END

SELECT SUM(TABLE_ROWS) 
     FROM INFORMATION_SCHEMA.TABLES 
     WHERE TABLE_SCHEMA = '{your_db}';

从文档中注意到:对于InnoDB表，行数只是用于SQL优化的粗略估计。您需要使用COUNT(*)来获得精确的计数(成本更高)。

简单的方法:

SELECT
  TABLE_NAME, SUM(TABLE_ROWS)
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = '{Your_DB}'
GROUP BY TABLE_NAME;

结果示例:

+----------------+-----------------+
| TABLE_NAME     | SUM(TABLE_ROWS) |
+----------------+-----------------+
| calls          |            7533 |
| courses        |             179 |
| course_modules |             298 |
| departments    |              58 |
| faculties      |             236 |
| modules        |             169 |
| searches       |           25423 |
| sections       |             532 |
| universities   |              57 |
| users          |           10293 |
+----------------+-----------------+