我们可以在show语句中使用concat（）group_concat（）等函数吗？

Question

例如，我运行命令

mysql> show tables;

DB中的表格

一个

b

C

d

我想使用它，如concat（'drop table'，tablename，';'）;

这样我的结果集就会变成

放表a;

下降表b;

丢弃表c;

等等....

Answer 1

使用21.24 The INFORMATION_SCHEMA TABLES Table。

尝试：

SELECT
  CONCAT('drop table ', `TABLE_NAME`, ';')
FROM
  `INFORMATION_SCHEMA`.`TABLES`
WHERE
  `TABLE_SCHEMA` = DATABASE() AND
  `TABLE_TYPE` = 'BASE TABLE';

SQL Fiddle demo

Answer 2

只是想添加，如果你想生成一个数据库列表，请使用类似的东西：

SELECT CONCAT('DROP DATABASE `', `table_schema`, '`;') FROM (
    SELECT `table_schema`
    FROM `INFORMATION_SCHEMA`.tables
    WHERE `table_schema` != "INFORMATION_SCHEMA" && `table_schema` != "performance_schema"
    GROUP BY `table_schema`
) as dbs

此外，如果要将所有drop database查询放在一行中，请使用GROUP_CONCAT

SELECT GROUP_CONCAT(ts SEPARATOR ' ') as drop_databases_query FROM (SELECT CONCAT('DROP DATABASE `', `table_schema`, '`;') as ts FROM (
    SELECT `table_schema`
    FROM `INFORMATION_SCHEMA`.tables
    WHERE `table_schema` != "INFORMATION_SCHEMA" && `table_schema` != "performance_schema"
    GROUP BY `table_schema`
) as dbs) as concatted

它会产生类似的结果

DROP DATABASE `mydb`; DROP DATABASE `mydb2`; DROP DATABASE `mysql`; DROP DATABASE `sys`;