diff --git a/bsition/backend/postgres/relations.py b/bsition/backend/postgres/relations.py
new file mode 100644
index 0000000..7f44c89
--- /dev/null
+++ b/bsition/backend/postgres/relations.py
@@ -0,0 +1,120 @@
+from psycopg2 import sql
+
+from bsition.backend.postgres.utils import get_connection
+
+
+def create_relations_tables():
+    conn = get_connection()
+    cur = conn.cursor()
+    cur.execute(
+        sql.SQL("""
+            CREATE TABLE table_access (
+                user_id INTEGER REFERENCES users(id),
+                table_id INTEGER,
+                access_type INTEGER CHECK (access_type IN (1, 2, 3)),
+                PRIMARY KEY (user_id, table_id) 
+            )
+            """)
+    )
+    cur.execute(
+        sql.SQL("""
+            CREATE TABLE doc_access (
+                user_id INTEGER REFERENCES users(id),
+                doc_id INTEGER,
+                access_type INTEGER CHECK (access_type IN (1, 2, 3)),
+                PRIMARY KEY (user_id, doc_id) 
+            )
+            """)
+    )
+    conn.commit()
+
+
+def give_access_table(user_id, table_id, access_type):
+    give_access(user_id, table_id, access_type, "table")
+
+
+def give_access_doc(user_id, table_id, access_type):
+    give_access(user_id, table_id, access_type, "doc")
+
+
+def give_access(user_id, id, access_type, destination):
+    if destination != "table" and destination != "doc":
+        raise "Invalid access destination"
+
+    conn = get_connection()
+    cur = conn.cursor()
+    cur.execute(
+        sql.SQL("""
+            INSERT INTO {destination_name} (user_id, {destination_id}, access_type) 
+            VALUES ({user_id}, {id}, {access_type})
+            ON CONFLICT (user_id, {destination_id}) DO UPDATE 
+            SET access_type = {access_type}
+        """).format(
+            user_id=sql.Literal(user_id),
+            destination_name=sql.Identifier(destination + "_access"),
+            destination_id=sql.Identifier(destination + "_id"),
+            access_type=sql.Literal(access_type),
+            id=sql.Literal(id)
+        )
+    )
+    conn.commit()
+
+
+def has_access_table(user_id, table_id):
+    return has_access(user_id, table_id, "table")
+
+
+def has_access_doc(user_id, table_id):
+    return has_access(user_id, table_id, "doc")
+
+
+def has_access(user_id, id, destination):
+    if destination != "table" and destination != "doc":
+        raise "Invalid access destination"
+    conn = get_connection()
+    cur = conn.cursor()
+    cur.execute(
+        sql.SQL("SELECT access_type FROM {destination_access} WHERE user_id = {user_id} AND {destination_id} = {id}").format(
+            user_id=sql.Literal(user_id),
+            destination_access=sql.Identifier(destination + "_access"),
+            destination_id=sql.Identifier(destination + "_id"),
+            id=sql.Literal(id)
+        )
+    )
+    return list(cur.fetchall())
+
+
+def deny_access_table(user_id, table_id):
+    return deny_access(user_id, table_id, "table")
+
+
+def deny_access_doc(user_id, table_id):
+    return deny_access(user_id, table_id, "doc")
+
+
+def deny_access(user_id, id, destination):
+    if destination != "table" and destination != "doc":
+        raise "Invalid access destination"
+
+    conn = get_connection()
+    cur = conn.cursor()
+    cur.execute(
+        sql.SQL("DELETE FROM {destination_access} WHERE user_id = {user_id} AND {destination_id} = {id}").format(
+            user_id=sql.Literal(user_id),
+            destination_access=sql.Identifier(destination + "_access"),
+            destination_id=sql.Identifier(destination + "_id"),
+            id=sql.Literal(id)
+        )
+    )
+    conn.commit()
+
+
+def get_accesible_documents(user_id):
+    conn = get_connection()
+    cur = conn.cursor()
+    cur.execute(
+        sql.SQL("SELECT doc_id FROM doc_access WHERE user_id = {user_id}").format(
+            user_id=sql.Literal(user_id)
+        )
+    )
+    return list(cur.fetchall())