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diff --git a/contrib/spi/refint.example b/contrib/spi/refint.example
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+--Column ID of table A is primary key:
+
+CREATE TABLE A (
+	ID	int4 not null
+);
+CREATE UNIQUE INDEX AI ON A (ID);
+
+--Columns REFB of table B and REFC of C are foreign keys referencing ID of A:
+
+CREATE TABLE B (
+	REFB	int4
+);
+CREATE INDEX BI ON B (REFB);
+
+CREATE TABLE C (
+	REFC	int4
+);
+CREATE INDEX CI ON C (REFC);
+
+--Trigger for table A:
+
+CREATE TRIGGER AT BEFORE DELETE OR UPDATE ON A FOR EACH ROW
+EXECUTE PROCEDURE
+check_foreign_key (2, 'cascade', 'ID', 'B', 'REFB', 'C', 'REFC');
+/*
+2	- means that check must be performed for foreign keys of 2 tables.
+cascade	- defines that corresponding keys must be deleted.
+ID	- name of primary key column in triggered table (A). You may
+	  use as many columns as you need.
+B	- name of (first) table with foreign keys.
+REFB	- name of foreign key column in this table. You may use as many
+	  columns as you need, but number of key columns in referenced
+	  table (A) must be the same.
+C	- name of second table with foreign keys.
+REFC	- name of foreign key column in this table.
+*/
+
+--Trigger for table B:
+
+CREATE TRIGGER BT BEFORE INSERT OR UPDATE ON B FOR EACH ROW
+EXECUTE PROCEDURE
+check_primary_key ('REFB', 'A', 'ID');
+
+/*
+REFB	- name of foreign key column in triggered (B) table. You may use as
+	  many columns as you need, but number of key columns in referenced
+	  table must be the same.
+A	- referenced table name.
+ID	- name of primary key column in referenced table.
+*/
+
+--Trigger for table C:
+
+CREATE TRIGGER CT BEFORE INSERT OR UPDATE ON C FOR EACH ROW
+EXECUTE PROCEDURE
+check_primary_key ('REFC', 'A', 'ID');
+
+-- Now try
+
+INSERT INTO A VALUES (10);
+INSERT INTO A VALUES (20);
+INSERT INTO A VALUES (30);
+INSERT INTO A VALUES (40);
+INSERT INTO A VALUES (50);
+
+INSERT INTO B VALUES (1);	-- invalid reference
+INSERT INTO B VALUES (10);
+INSERT INTO B VALUES (30);
+INSERT INTO B VALUES (30);
+
+INSERT INTO C VALUES (11);	-- invalid reference
+INSERT INTO C VALUES (20);
+INSERT INTO C VALUES (20);
+INSERT INTO C VALUES (30);
+
+DELETE FROM A WHERE ID = 10;
+DELETE FROM A WHERE ID = 20;
+DELETE FROM A WHERE ID = 30;
+
+SELECT * FROM A;
+SELECT * FROM B;
+SELECT * FROM C;