[英]MySQL Querying Multiple Databases
I have multiple databases and I need to search for a value in a table and set it to NULL in all instances across all databases. 我有多个数据库,我需要在表中搜索一个值,然后在所有数据库的所有实例中将其设置为NULL。
I know how to query individual databases after "USE 'DBName'" is called to select a particular database. 我知道在调用“ USE'DBName'”以选择特定数据库后如何查询单个数据库。
How do I loop all databases? 如何循环所有数据库?
Use the SHOW DATABASES query to list all databases. 使用SHOW DATABASES查询列出所有数据库。
You don't need to USE
the database to query its tables: 您不需要USE
数据库来查询其表:
SELECT something FROM databasename.sometable
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