If you want to know all primary key & Foreign key
constraint in your SQL Server data base or a particular data table then use
below SQL Statement.
Know Primary Key Constraint in Entire SQL Data Base:

Image 1.
SELECT I.name AS PrimaryKeyName,
OBJECT_NAME(IC.OBJECT_ID) AS TableName,
COL_NAME(IC.OBJECT_ID,IC.column_id) AS
PrimaryKeyColumnName
FROM SYS.INDEXES AS I
INNER JOIN SYS.INDEX_COLUMNS
AS IC
ON I.OBJECT_ID = IC.OBJECT_ID
AND I.index_id = IC.index_id
WHERE I.is_primary_key = 1 ORDER BY OBJECT_NAME(IC.OBJECT_ID)
If you want to know Primary key
constraint on any particular table then use below statement:

Image 2.
To know Foreign Key Constraint use below
SQL Statement:
SELECT FR.name AS ForeignKeyName,
OBJECT_NAME(FR.parent_object_id) AS TableName,
COL_NAME(FC.parent_object_id,
FC.parent_column_id) AS ColumnName,
OBJECT_NAME (FR.referenced_object_id) AS
ReferenceTableName,
COL_NAME(fc.referenced_object_id,
fc.referenced_column_id) AS
ReferenceColumnName
FROM SYS.FOREIGN_KEYS AS FR
INNER JOIN SYS.FOREIGN_KEY_COLUMNS
AS FC
ON FR.OBJECT_ID
= FC.constraint_object_id
ORDER BY OBJECT_NAME(FR.parent_object_id)