New way to fix BUG#19243 "wrong LAST_INSERT_ID() after ON DUPLICATE KEY UPDATE".

This bug report was two problems:
1) LAST_INSERT_ID() returns a value which does not exist in the table
2) the reporter would want it to return the autoinc id of the updated
row.
1) is a real bug, 2) is a feature request.
In July I implemented 2) in 5.1 (which automatically fixes 1).
This has not yet been documented or released, so is changeable.
Precisely, recently Paul and a user found an easy workaround to give
2), which works in 4.1-5.0-5.1. So I can revert my code for 2),
because it's not needed, that's what I do here;
we forget about 2) (we will document the workaround).
But when I revert my code for 2), 1) comes back. We solve 1) by saying
that if INSERT ON DUPLICATE KEY UPDATE updates a row, it's like a
regular UPDATE: LAST_INSERT_ID() should not be affected (instead of
returning a non-existent value).
So note: no behaviour change compared to the last released 5.1; just
a bugfix for 1).


mysql-test/r/innodb_mysql.result:
  result update
mysql-test/t/innodb_mysql.test:
      test for the new way to fix BUG#19243: that if INSERT ON DUPLICATE
      KEY UPDATE updates a row, SELECT LAST_INSERT_ID() is not affected.
      Test of the workaround for people who want SELECT LAST_INSERT_ID()
      to return the autoinc id of the updated row.
sql/sql_insert.cc:
  No need to change LAST_INSERT_ID() if INSERT ON DUPLICATE KEY UPDATE
  updates a row, there is a workaround to achieve this without changing
  code: just add "autoinc_col=LAST_INSERT_ID(autoinc_col)" to your
  ON DUPLICATE KEY UPDATE clause.
  Prevent LAST_INSERT_ID() to contain an inexistent value in this case:
  if the row is updated it should be like a regular UPDATE: don't
  affect LAST_INSERT_ID() (achieved by marking that we didn't generate
  an id for this row: insert_id_for_cur_row=0).

mysql-test/r/innodb_mysql.result

@@ -432,22 +432,44 @@ ifnull( c,
 0 ) + 1;
 select last_insert_id();
 last_insert_id()
-1
+2
+select last_insert_id(0);
+last_insert_id(0)
+0
+insert into t2 ( a ) values ( 6 ) on duplicate key update c =
+ifnull( c,
+0 ) + 1;
+select last_insert_id();
+last_insert_id()
+0
 select * from t2;
 k	a	c
-1	6	1
+1	6	2
 2	7	NULL
 insert ignore into t2 values (null,6,1),(10,8,1);
 select last_insert_id();
 last_insert_id()
-1
+0
 insert ignore into t2 values (null,6,1),(null,8,1),(null,15,1),(null,20,1);
 select last_insert_id();
 last_insert_id()
 11
 select * from t2;
 k	a	c
-1	6	1
+1	6	2
+2	7	NULL
+10	8	1
+11	15	1
+12	20	1
+insert into t2 ( a ) values ( 6 ) on duplicate key update c =
+ifnull( c,
+0 ) + 1, k=last_insert_id(k);
+select last_insert_id();
+last_insert_id()
+1
+select * from t2;
+k	a	c
+1	6	3
 2	7	NULL
 10	8	1
 11	15	1

mysql-test/t/innodb_mysql.test

@@ -369,8 +369,8 @@ insert into t1 values('aaa');
 drop table t1;
 
 # Fix for BUG#19243 "wrong LAST_INSERT_ID() after ON DUPLICATE KEY
-# UPDATE": now LAST_INSERT_ID() will return the id of the updated
-# row.
+# UPDATE": if the row is updated, it's like a regular UPDATE:
+# LAST_INSERT_ID() is not affected.
 CREATE TABLE `t2` (
   `k` int(11) NOT NULL auto_increment,
   `a` int(11) default NULL,
@@ -390,6 +390,12 @@ insert into t2 ( a ) values ( 6 ) on duplicate key update c =
 ifnull( c,
 0 ) + 1;
 select last_insert_id();
+# test again when last_insert_id() is 0 initially
+select last_insert_id(0);
+insert into t2 ( a ) values ( 6 ) on duplicate key update c =
+ifnull( c,
+0 ) + 1;
+select last_insert_id();
 select * from t2;
 
 # Test of LAST_INSERT_ID() when autogenerated will fail:
@@ -402,5 +408,14 @@ insert ignore into t2 values (null,6,1),(null,8,1),(null,15,1),(null,20,1);
 select last_insert_id();
 select * from t2;
 
-drop table t2;
+# Test of the workaround which enables people to know the id of the
+# updated row in INSERT ON DUPLICATE KEY UPDATE, by using
+# LAST_INSERT_ID(autoinc_col) in the UPDATE clause.
 
+insert into t2 ( a ) values ( 6 ) on duplicate key update c =
+ifnull( c,
+0 ) + 1, k=last_insert_id(k);
+select last_insert_id();
+select * from t2;
+
+drop table t2;

sql/sql_insert.cc

@@ -1145,16 +1145,15 @@ int write_record(THD *thd, TABLE *table,COPY_INFO *info)
 	}
         info->updated++;
         /*
-          If ON DUP KEY UPDATE updates a row instead of inserting one, and
-          there is an auto_increment column, then SELECT LAST_INSERT_ID()
-          returns the id of the updated row:
+          If ON DUP KEY UPDATE updates a row instead of inserting one, it's
+          like a regular UPDATE statement: it should not affect the value of a
+          next SELECT LAST_INSERT_ID() or mysql_insert_id().
+          Except if LAST_INSERT_ID(#) was in the INSERT query, which is
+          handled separately by THD::arg_of_last_insert_id_function.
         */
+        insert_id_for_cur_row= table->file->insert_id_for_cur_row= 0;
         if (table->next_number_field)
-        {
-          longlong field_val= table->next_number_field->val_int();
-          thd->record_first_successful_insert_id_in_cur_stmt(field_val);
-          table->file->adjust_next_insert_id_after_explicit_value(field_val);
-        }
+          table->file->adjust_next_insert_id_after_explicit_value(table->next_number_field->val_int());
         trg_error= (table->triggers &&
                     table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
                                                       TRG_ACTION_AFTER, TRUE));