将mysql查询应用于数据库中的每个表

is there a way to apply a query to each table in a mysql database?

有没有办法将查询应用于mysql数据库中的每个表？

Something like

就像是

SELECT count(*) FROM {ALL TABLES}
-- gives the number of count(*) in each Table

and

和

DELETE FROM {ALL TABLES}
-- Like DELETE FROM TABLE applied on each Table

2 个解决方案

#1

select sum(table_rows) as total_rows
from information_schema.tables
where table_schema = 'your_db_name'

beware this is just an approximate value

要注意这只是一个近似值

In order to delete the contents of all your tables you can do something like this

要删除所有表格的内容，您可以执行以下操作

select concat('truncate ',table_name,';')
from information_schema.tables
where table_schema = 'your_db_name'

Then run the output of this query.

然后运行此查询的输出。

UPDATE.

UPDATE。

This is a stored procedure to apply truncate table to all tables in a specific database

这是将truncate table应用于特定数据库中的所有表的存储过程

delimiter //
drop procedure if exists delete_contents //
create procedure delete_contents (in db_name varchar(100))
begin
declare finish int default 0;
declare tab varchar(100);
declare cur_tables cursor for select table_name from information_schema.tables where table_schema = db_name and table_type = 'base table';
declare continue handler for not found set finish = 1;
open cur_tables;
my_loop:loop
fetch cur_tables into tab;
if finish = 1 then
leave my_loop;
end if;

set @str = concat('truncate ', tab);
prepare stmt from @str;
execute stmt;
deallocate prepare stmt;
end loop;
close cur_tables;
end; //
delimiter ;

call delete_contents('your_db_name');

#2

if tables are related by any field you can use alias of tables like

如果表与任何字段相关，则可以使用表的别名

select count(*) from table1 tb1, table2 tb2, table3 tb3 where
tb1.field1 = tb2.field2 and tb2.field2 = tb3.field3

similary,

与之相似，

delete from table1 tb1, table2 tb2, table3 tb3 where
tb1.field1 = tb2.field2 and tb2.field2 = tb3.field3

you can include conditions as per you requirements.

您可以根据您的要求包括条件。

If tables have no relation then use below

如果表没有关系，请在下面使用

SELECT
  (SELECT COUNT(*) FROM table1 WHERE someCondition) as count1, 
  (SELECT COUNT(*) FROM table2 WHERE someCondition) as count2,
  (SELECT COUNT(*) FROM table3 WHERE someCondition) as count3

you can remove where clause if there is no conditions.

如果没有条件，你可以删除where子句。

OUTPUT:

OUTPUT：

|count1 | count2 | count3|

| count1 | count2 |共3个记录|

|50 |36 |21 |

| 50 | 36 | 21 |

#1

select sum(table_rows) as total_rows
from information_schema.tables
where table_schema = 'your_db_name'