How do I see all foreign keys to a table or column?
For a Table:
SELECT
TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME, REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
REFERENCED_TABLE_SCHEMA = '<database>' AND
REFERENCED_TABLE_NAME = '<table>';
For a Column:
SELECT
TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME, REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
REFERENCED_TABLE_SCHEMA = '<database>' AND
REFERENCED_TABLE_NAME = '<table>' AND
REFERENCED_COLUMN_NAME = '<column>';
Basically, we changed REFERENCED_TABLE_NAME with REFERENCED_COLUMN_NAME in the where clause.
How can I list all foreign keys referencing a given table in SQL Server?
Not sure why no one suggested but I use sp_fkeys
to query foreign keys for a given table:
EXEC sp_fkeys 'TableName'
You can also specify the schema:
EXEC sp_fkeys @pktable_name = 'TableName', @pktable_owner = 'dbo'
Without specifying the schema, the docs state the following:
If pktable_owner is not specified, the default table visibility rules
of the underlying DBMS apply.In SQL Server, if the current user owns a table with the specified
name, that table's columns are returned. If pktable_owner is not
specified and the current user does not own a table with the specified
pktable_name, the procedure looks for a table with the specified
pktable_name owned by the database owner. If one exists, that table's
columns are returned.
How to list table foreign keys
You can do this via the information_schema tables. For example:
SELECT
tc.table_schema,
tc.constraint_name,
tc.table_name,
kcu.column_name,
ccu.table_schema AS foreign_table_schema,
ccu.table_name AS foreign_table_name,
ccu.column_name AS foreign_column_name
FROM
information_schema.table_constraints AS tc
JOIN information_schema.key_column_usage AS kcu
ON tc.constraint_name = kcu.constraint_name
AND tc.table_schema = kcu.table_schema
JOIN information_schema.constraint_column_usage AS ccu
ON ccu.constraint_name = tc.constraint_name
AND ccu.table_schema = tc.table_schema
WHERE tc.constraint_type = 'FOREIGN KEY' AND tc.table_name='mytable';
How can I list all foreign keys in a Table?
The below code snippet could be put to some use and modified by your further requirement -
This would pull the column level details such as data type
, length
, precision
, scale
etc...
SELECT obj.name AS FK_NAME,
sch.name AS [schema_name],
tab1.name AS [table],
col1.name AS [column],
tab2.name AS [referenced_table],
col2.name AS [referenced_column],
TY.[name] AS system_data_type, col1.[max_length],col1.[precision], col1.[scale], col1.[is_nullable], col1.[is_ansi_padded]
FROM sys.foreign_key_columns fkc
INNER JOIN sys.objects obj
ON obj.object_id = fkc.constraint_object_id
INNER JOIN sys.tables tab1
ON tab1.object_id = fkc.parent_object_id
INNER JOIN sys.schemas sch
ON tab1.schema_id = sch.schema_id
INNER JOIN sys.columns col1
ON col1.column_id = parent_column_id AND col1.object_id = tab1.object_id
INNER JOIN sys.tables tab2
ON tab2.object_id = fkc.referenced_object_id
INNER JOIN sys.columns col2
ON col2.column_id = referenced_column_id AND col2.object_id = tab2.object_id
INNER JOIN sys.[types] TY ON col1.[system_type_id] = TY.[system_type_id] AND col1.[user_type_id] = TY.[user_type_id]
AND tab1.name = 'TableName1'
How can I find out what FOREIGN KEY constraint references a table in SQL Server?
Here it is:
SELECT
OBJECT_NAME(f.parent_object_id) TableName,
COL_NAME(fc.parent_object_id,fc.parent_column_id) ColName
FROM
sys.foreign_keys AS f
INNER JOIN
sys.foreign_key_columns AS fc
ON f.OBJECT_ID = fc.constraint_object_id
INNER JOIN
sys.tables t
ON t.OBJECT_ID = fc.referenced_object_id
WHERE
OBJECT_NAME (f.referenced_object_id) = 'YourTableName'
This way, you'll get the referencing table and column name.
Edited to use sys.tables instead of generic sys.objects as per comment suggestion.
Thanks, marc_s
MySQL - How to list all tables that have a foreign key referring to my table's primary key?
I guess the last answer was almost correct. just change the table from "key_column" to "key_column_usage.
Cheers
Nikao
How can I get the foreign keys of a table in mysql
Simple way to get foreign keys for given table:
SELECT
`column_name`,
`referenced_table_schema` AS foreign_db,
`referenced_table_name` AS foreign_table,
`referenced_column_name` AS foreign_column
FROM
`information_schema`.`KEY_COLUMN_USAGE`
WHERE
`constraint_schema` = SCHEMA()
AND
`table_name` = 'your-table-name-here'
AND
`referenced_column_name` IS NOT NULL
ORDER BY
`column_name`;
How can I select all tables with a certain amount of foreign keys in them?
Run this query on for your target database. Please make sure the query returning correct data by some manual checking before rely on it :)
SELECT [Table Name],COUNT(*)
FROM
(
SELECT fk_tab.name as [Table Name],
fk.name [FK_Name]
FROM sys.foreign_keys fk
INNER JOIN sys.tables fk_tab
ON fk_tab.object_id = fk.parent_object_id
)A
GROUP BY [Table Name]
ORDER BY COUNT(*) DESC
For MySQL, Can your please try this. I simply copied it from Here
select concat(fks.constraint_schema, '.', fks.table_name) as foreign_table,
'->' as rel,
concat(fks.unique_constraint_schema, '.', fks.referenced_table_name)
as primary_table,
fks.constraint_name,
group_concat(kcu.column_name
order by position_in_unique_constraint separator ', ')
as fk_columns
from information_schema.referential_constraints fks
join information_schema.key_column_usage kcu
on fks.constraint_schema = kcu.table_schema
and fks.table_name = kcu.table_name
and fks.constraint_name = kcu.constraint_name
group by fks.constraint_schema,
fks.table_name,
fks.unique_constraint_schema,
fks.referenced_table_name,
fks.constraint_name
order by fks.constraint_schema,
fks.table_name;
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