How to find foreign key dependencies in SQL Server?

The following query will help to get you started. It lists all Foreign Key Relationships within the current database.

SELECT
    FK_Table = FK.TABLE_NAME,
    FK_Column = CU.COLUMN_NAME,
    PK_Table = PK.TABLE_NAME,
    PK_Column = PT.COLUMN_NAME,
    Constraint_Name = C.CONSTRAINT_NAME
FROM
    INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK
    ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK
    ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU
    ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME
INNER JOIN (
            SELECT
                i1.TABLE_NAME,
                i2.COLUMN_NAME
            FROM
                INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1
            INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2
                ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME
            WHERE
                i1.CONSTRAINT_TYPE = 'PRIMARY KEY'
           ) PT
    ON PT.TABLE_NAME = PK.TABLE_NAME

You can also view relationships graphically within SQL Server Management studio within Database Diagrams.

try: sp_help [table_name]

you will get all information about table, including all foreign keys

I think this script is less expensive:

SELECT f.name AS ForeignKey, OBJECT_NAME(f.parent_object_id) AS TableName,
    COL_NAME(fc.parent_object_id, fc.parent_column_id) AS ColumnName,
    OBJECT_NAME (f.referenced_object_id) AS ReferenceTableName,
    COL_NAME(fc.referenced_object_id, fc.referenced_column_id) AS ReferenceColumnName
FROM sys.foreign_keys AS f
INNER JOIN sys.foreign_key_columns AS fc
ON f.OBJECT_ID = fc.constraint_object_id

One that I really like to use is called SQL Dependency Tracker by Red Gate Software. You can put in any database object(s) such as tables, stored procedures, etc. and it will then automatically draw the relationship lines between all the other objects that rely on your selected item(s).

Gives a very good graphical representation of the dependencies in your schema.

You can Use INFORMATION_SCHEMA.KEY_COLUMN_USAGE and sys.foreign_key_columns in order to get the foreign key metadata for a table i.e. Constraint name, Reference table and Reference column etc.

Below is the query:

SELECT  CONSTRAINT_NAME, COLUMN_NAME, ParentTableName, RefTableName,RefColName FROM 
    (SELECT CONSTRAINT_NAME,COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_NAME = '<tableName>') constraint_details
    INNER JOIN  
    (SELECT ParentTableName, RefTableName,name ,COL_NAME(fc.referenced_object_id,fc.referenced_column_id) RefColName  FROM (SELECT object_name(parent_object_id) ParentTableName,object_name(referenced_object_id) RefTableName,name,OBJECT_ID  FROM sys.foreign_keys WHERE parent_object_id = object_id('<tableName>') ) f 
    INNER JOIN   
    sys.foreign_key_columns AS fc  ON  f.OBJECT_ID = fc.constraint_object_id ) foreign_key_detail 
    on foreign_key_detail.name = constraint_details.CONSTRAINT_NAME

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]
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

It will give you:

The FK itself Schema that the FK belongs to

• The "referencing table" or the table that has the FK
• The "referencing column" or the column inside referencing table that points to the FK
• The "referenced table" or the table that has the key column that your FK is pointing to
• The "referenced column" or the column that is the key that your FK is pointing to