The query below returns foreign key constraint columns defined in a database.
Query
select schema_name(fk_tab.schema_id) + '.' + fk_tab.name as foreign_table,
    '>-' as rel,
    schema_name(pk_tab.schema_id) + '.' + pk_tab.name as primary_table,
    fk_cols.constraint_column_id as no, 
    fk_col.name as fk_column_name,
    ' = ' as [join],
    pk_col.name as pk_column_name,
    fk.name as fk_constraint_name
from sys.foreign_keys as fk
    inner join sys.tables as fk_tab
        on fk_tab.object_id = fk.parent_object_id
    inner join sys.tables as pk_tab
        on pk_tab.object_id = fk.referenced_object_id
    inner join sys.foreign_key_columns as fk_cols
        on fk_cols.constraint_object_id = fk.object_id
    inner join sys.columns as fk_col
        on fk_col.column_id = fk_cols.parent_column_id
            and fk_col.object_id = fk_tab.object_id
    inner join sys.columns as pk_col
        on pk_col.column_id = fk_cols.referenced_column_id
            and pk_col.object_id = pk_tab.object_id
order by schema_name(fk_tab.schema_id) + '.' + fk_tab.name,
    schema_name(pk_tab.schema_id) + '.' + pk_tab.name,
    fk_cols.constraint_column_id
Columns
- foreign_table - foreign table name with schema name
- rel - relationship symbol implicating direction
- primary_table - primary (referenced) table name with schema name
- no - id of the column in key. Single column keys always have 1, composite keys have 1, 2, ... n for each column of the key
- fk_column_name - foreign table column
- join - "=" symbol indicating join operation for pair of columns
- pk_column_name - primary (referenced) table column
- fk_constraint_name - foreign key constraint name
Rows
- One row: represents one foreign key column. If the foreign key consists of multiple columns (composite key), each column appears separately.
- Scope of rows: all foreign keys in a database and their columns
- Ordered by: foreign table schema name and table name and column ordinal position in the key
Sample results
Foreign key constraints in the AdventureWorksLT database with their columns:

 
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                 
                                                             
                                                             
                                                             
                                                             
                                                                 
                                                             
                                                             
                                                                 
                                                             
                                                             
                                                             
                                                             Rene Castro
                                                                        Rene Castro
                                 Azure SQL Database
                                                                Azure SQL Database
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