如何在一个查询中从多个数据库中选择记录？

Question

I want to use multiple database because I have 1 database which contain 40 tables and it doesnt seem good.Thats why I want to create another database but problem is I am not able to join this databases at one query for example I have 'core' database and it contains users table which has user_id column second database is post database and I need get user_id from users table which is in 'core' database like below

SELECT post_message from posts where 'core'.user_id=123 

is that possible?or should I stick with one database?I have also foreign key problem which is related with database relation.

Answer 1

If it is SQL SERVER Product, You can call the Object residing on another DB like below

SELECT * FROM [DB_NAME].[Schema_Name].[Table_NAME]

For Example:

SELECT * FROM DB1.dbo.Employee

For MySQL : Please go through the below ans Select columns across different databases