Fix bug#15028 Multitable update returns different numbers of matched rows

depending on table order

multi_update::send_data() was counting updates, not updated rows. Thus if one 
record have several updates it will be counted several times in 'rows matched'
but updated only once.

multi_update::send_data() now counts only unique rows.


sql/sql_update.cc:
  Fix bug#15028  Multitable update returns different numbers of matched rows
  depending on table order
  multi_update::send_data() now counts only unique rows.
mysql-test/t/update.test:
  Test case for bug#15028 Multitable update returns different numbers of matched rows depending on table order
mysql-test/r/update.result:
  Test case for bug#15028 Multitable update returns different numbers of matched rows depending on table order

1 files changed, 13 insertions, 0 deletions

diff --git a/mysql-test/r/update.result b/mysql-test/r/update.result
index 74c628f96c4..7854fd773a1 100644
--- a/mysql-test/r/update.result
+++ b/mysql-test/r/update.result
@@ -345,3 +345,16 @@ f1
 2000-01-01
 2002-02-02
 drop table t1;
+create table t1 (f1 int);
+create table t2 (f2 int);
+insert into t1 values(1),(2);
+insert into t2 values(1),(1);
+update t1,t2 set f1=3,f2=3 where f1=f2 and f1=1;
+affected rows: 3
+info: Rows matched: 3  Changed: 3  Warnings: 0
+update t2 set f2=1;
+update t1 set f1=1 where f1=3;
+update t2,t1 set f1=3,f2=3 where f1=f2 and f1=1;
+affected rows: 3
+info: Rows matched: 3  Changed: 3  Warnings: 0
+drop table t1,t2;