Apply InnoDB-specific parts of the fix for bug #9680, wrong error from

cascading update.

handler/ha_innodb.cc

@@ -457,6 +457,10 @@ convert_error_code_to_mysql(
 
     		return(HA_ERR_FOUND_DUPP_KEY);
 
+  	} else if (error == (int) DB_FOREIGN_DUPLICATE_KEY) {
+
+		return(HA_ERR_FOREIGN_DUPLICATE_KEY);
+
  	} else if (error == (int) DB_RECORD_NOT_FOUND) {
 
     		return(HA_ERR_NO_ACTIVE_RECORD);

include/db0err.h

@@ -57,6 +57,10 @@ Created 5/24/1996 Heikki Tuuri
 					buffer pool (for big transactions,
 					InnoDB stores the lock structs in the
 					buffer pool) */
+#define DB_FOREIGN_DUPLICATE_KEY 46	/* foreign key constraints
+					activated by the operation would
+					lead to a duplicate key in some
+					table */
 
 /* The following are partial failure codes */
 #define DB_FAIL 		1000

mysql-test/innodb.result

@@ -3213,3 +3213,21 @@ drop trigger t2t;
 drop trigger t3t;
 drop trigger t4t;
 drop table t1, t2, t3, t4, t5;
+CREATE TABLE t1 (
+field1 varchar(8) NOT NULL DEFAULT '',
+field2 varchar(8) NOT NULL DEFAULT '',
+PRIMARY KEY  (field1, field2)
+) ENGINE=InnoDB;
+CREATE TABLE t2 (
+field1 varchar(8) NOT NULL DEFAULT '' PRIMARY KEY,
+FOREIGN KEY (field1) REFERENCES t1 (field1)
+ON DELETE CASCADE ON UPDATE CASCADE
+) ENGINE=InnoDB;
+INSERT INTO t1 VALUES ('old', 'somevalu');
+INSERT INTO t1 VALUES ('other', 'anyvalue');
+INSERT INTO t2 VALUES ('old');
+INSERT INTO t2 VALUES ('other');
+UPDATE t1 SET field1 = 'other' WHERE field2 = 'somevalu';
+ERROR 23000: Upholding foreign key constraints for table 't1', entry 'other-somevalu', key 1 would lead to a duplicate entry
+DROP TABLE t2;
+DROP TABLE t1;

mysql-test/innodb.test

@@ -2106,3 +2106,32 @@ drop trigger t4t;
 drop table t1, t2, t3, t4, t5;
 disconnect a;
 disconnect b;
+
+#
+# Test that cascading updates leading to duplicate keys give the correct
+# error message (bug #9680)
+#
+
+CREATE TABLE t1 (
+  field1 varchar(8) NOT NULL DEFAULT '',
+  field2 varchar(8) NOT NULL DEFAULT '',
+  PRIMARY KEY  (field1, field2)
+) ENGINE=InnoDB;
+
+CREATE TABLE t2 (
+  field1 varchar(8) NOT NULL DEFAULT '' PRIMARY KEY,
+  FOREIGN KEY (field1) REFERENCES t1 (field1)
+    ON DELETE CASCADE ON UPDATE CASCADE
+) ENGINE=InnoDB;
+
+INSERT INTO t1 VALUES ('old', 'somevalu');
+INSERT INTO t1 VALUES ('other', 'anyvalue');
+
+INSERT INTO t2 VALUES ('old');
+INSERT INTO t2 VALUES ('other');
+
+--error ER_FOREIGN_DUPLICATE_KEY
+UPDATE t1 SET field1 = 'other' WHERE field2 = 'somevalu';
+
+DROP TABLE t2;
+DROP TABLE t1;

row/row0ins.c

@@ -1386,6 +1386,21 @@ run_again:
 						thr, foreign, &pcur, entry,
 									&mtr);
 					if (err != DB_SUCCESS) {
+						/* Since reporting a plain
+						"duplicate key" error
+						message to the user in
+						cases where a long CASCADE
+						operation would lead to a
+						duplicate key in some
+						other table is very
+						confusing, map duplicate
+						key errors resulting from
+						FK constraints to a
+						separate error code. */
+				    
+						if (err == DB_DUPLICATE_KEY) {
+						    err = DB_FOREIGN_DUPLICATE_KEY;
+						}
 
 						break;
 					}

row/row0mysql.c

@@ -473,8 +473,9 @@ handle_new_error:
 	ut_a(err != DB_SUCCESS);
 	
 	trx->error_state = DB_SUCCESS;
-
-	if (err == DB_DUPLICATE_KEY) {
+	
+	if ((err == DB_DUPLICATE_KEY)
+		|| (err == DB_FOREIGN_DUPLICATE_KEY)) {
            	if (savept) {
 			/* Roll back the latest, possibly incomplete
 			insertion or update */