Question

What can be the possible query for listing all/one the table(s) that are being referenced from a given table please?

Actually I can list the tables which are referenced by a given table with the following query I found on search.

use INFORMATION_SCHEMA;

select TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME,
REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME from KEY_COLUMN_USAGE where
REFERENCED_TABLE_NAME = '<table>';

But what I need is the reverse side of this. That is a list of tables that are being referenced from a given table.

Would be great to have a solution.. Thanks in advance.

Answer 1

You can use:

SELECT TABLE_NAME 
    FROM information_schema.KEY_COLUMN_USAGE 
WHERE REFERENCED_TABLE_NAME = 'yourtable';

To check which tables link to ‘yourtable’.

You can use:

SELECT REFERENCED_TABLE_NAME 
    FROM information_schema.KEY_COLUMN_USAGE 
WHERE TABLE_NAME = 'yourtable';

to search the other way around. Make sure to use correct foreign key declaration in the create table statement in order for this table to be filled correctly!

mysql> describe KEY_COLUMN_USAGE;
+-------------------------------+--------------+------+-----+---------+-------+
| Field                         | Type         | Null | Key | Default | Extra |
+-------------------------------+--------------+------+-----+---------+-------+
| CONSTRAINT_CATALOG            | varchar(512) | NO   |     |         |       |
| CONSTRAINT_SCHEMA             | varchar(64)  | NO   |     |         |       |
| CONSTRAINT_NAME               | varchar(64)  | NO   |     |         |       |
| TABLE_CATALOG                 | varchar(512) | NO   |     |         |       |
| TABLE_SCHEMA                  | varchar(64)  | NO   |     |         |       |
| TABLE_NAME                    | varchar(64)  | NO   |     |         |       |
| COLUMN_NAME                   | varchar(64)  | NO   |     |         |       |
| ORDINAL_POSITION              | bigint(10)   | NO   |     | 0       |       |
| POSITION_IN_UNIQUE_CONSTRAINT | bigint(10)   | YES  |     | NULL    |       |
| REFERENCED_TABLE_SCHEMA       | varchar(64)  | YES  |     | NULL    |       |
| REFERENCED_TABLE_NAME         | varchar(64)  | YES  |     | NULL    |       |
| REFERENCED_COLUMN_NAME        | varchar(64)  | YES  |     | NULL    |       |
+-------------------------------+--------------+------+-----+---------+-------+