How to find all the relations between all mysql tables?

Question

How to find all the relations between all MySQL tables? If for example, I want to know the relation of tables in a database of having around 100 tables.

Is there any

Answer 1

Try

SELECT
`TABLE_NAME`,
`COLUMN_NAME`,
`REFERENCED_TABLE_NAME`,
`REFERENCED_COLUMN_NAME`
FROM `information_schema`.`KEY_COLUMN_USAGE`
WHERE `CONSTRAINT_SCHEMA` = 'YOUR_DATABASE_NAME' AND
`REFERENCED_TABLE_SCHEMA` IS NOT NULL AND
`REFERENCED_TABLE_NAME` IS NOT NULL AND
`REFERENCED_COLUMN_NAME` IS NOT NULL

do not forget to replace YOUR_DATABASE_NAME with your database name!

Answer 2

SELECT 
    count(1) totalrelationships ,
    c.table_name tablename,
    CONCAT(' ',GROUP_CONCAT(c.column_name ORDER BY ordinal_position SEPARATOR ', ')) columnname,
    CONCAT(' ',GROUP_CONCAT(c.column_type ORDER BY ordinal_position SEPARATOR ', ')) columntype    
FROM
    information_schema.columns c RIGHT JOIN
    (SELECT column_name , column_type FROM information_schema.columns WHERE 
    -- column_key in ('PRI','MUL') AND  -- uncomment this line if you want to see relations only with indexes
    table_schema = DATABASE() AND table_name = 'YourTableName') AS p
    USING (column_name,column_type)
WHERE
    c.table_schema = DATABASE()
    -- AND c.table_name != 'YourTableName'
    GROUP BY tablename
    -- HAVING (locate(' YourColumnName',columnname) > 0) -- uncomment this line to search for specific column 
    ORDER BY totalrelationships desc, columnname
;

Answer 3

Based on xudre's answer, you can execute the following to see all the relations of a schema:

SELECT 
  `TABLE_SCHEMA`,                          -- Foreign key schema
  `TABLE_NAME`,                            -- Foreign key table
  `COLUMN_NAME`,                           -- Foreign key column
  `REFERENCED_TABLE_SCHEMA`,               -- Origin key schema
  `REFERENCED_TABLE_NAME`,                 -- Origin key table
  `REFERENCED_COLUMN_NAME`                 -- Origin key column
FROM `INFORMATION_SCHEMA`.`KEY_COLUMN_USAGE`
WHERE `TABLE_SCHEMA` = 'YourSchema'
AND   `REFERENCED_TABLE_NAME` IS NOT NULL  -- Only tables with foreign keys

What I want in most cases is to know all FKs that point to a specific table. In this case I run:

SELECT 
  `TABLE_SCHEMA`,                          -- Foreign key schema
  `TABLE_NAME`,                            -- Foreign key table
  `COLUMN_NAME`                            -- Foreign key column
FROM `INFORMATION_SCHEMA`.`KEY_COLUMN_USAGE`  
WHERE `TABLE_SCHEMA` = 'YourSchema'
AND   `REFERENCED_TABLE_NAME` = 'YourTableName'