Bug#11745891 - LAST_INSERT(ID) DOES NOT SUPPORT BIGINT UNSIGNED

Neeraj Bisht · Neeraj Bisht · commit d974ea7f534e · 2012-10-16T23:26:35.000+05:30
Problem:-
using last_insert_id() on an auto_incremented bigint unsigned does
not work for values which are greater than max-bigint-signed.

Analysis:-
last_insert_id() returns the first auto_incremented value for a column
and an auto_incremented value can have only positive values.

In our code, when we are initializing a last_insert_id object, we are
taking it as a signed BIGINT, So when the auto_incremented value reaches
greater than max signed bigint, last_insert_id gives negative result.

Solution:
When we are fetching the value from last_insert_id, We are setting the 
unsigned_flag, so that it take only unsigned BIGINT value.
diff --git a/sql/item_func.cc b/sql/item_func.cc
@@ -4023,7 +4023,8 @@ longlong Item_func_last_insert_id::val_int()
     thd->first_successful_insert_id_in_prev_stmt= value;
     return value;
   }
-  return thd->read_first_successful_insert_id_in_prev_stmt();
+  return
+    static_cast<longlong>(thd->read_first_successful_insert_id_in_prev_stmt());
 }
 
 
diff --git a/sql/item_func.h b/sql/item_func.h
@@ -1130,6 +1130,7 @@ class Item_func_last_insert_id :public Item_int_func
   const char *func_name() const { return "last_insert_id"; }
   void fix_length_and_dec()
   {
+    unsigned_flag= TRUE;
     if (arg_count)
       max_length= args[0]->max_length;
   }

Original file line number	Diff line number	Diff line change
`@@ -4023,7 +4023,8 @@ longlong Item_func_last_insert_id::val_int()`
`4023`	`4023`	`thd->first_successful_insert_id_in_prev_stmt= value;`
`4024`	`4024`	`return value;`
`4025`	`4025`	`}`
`4026`		`- return thd->read_first_successful_insert_id_in_prev_stmt();`
	`4026`	`+ return`
	`4027`	`+ static_cast<longlong>(thd->read_first_successful_insert_id_in_prev_stmt());`
`4027`	`4028`	`}`
`4028`	`4029`
`4029`	`4030`
Original file line number	Diff line number	Diff line change
`@@ -1130,6 +1130,7 @@ class Item_func_last_insert_id :public Item_int_func`
`1130`	`1130`	`const char *func_name() const { return "last_insert_id"; }`
`1131`	`1131`	`void fix_length_and_dec()`
`1132`	`1132`	`{`
	`1133`	`+ unsigned_flag= TRUE;`
`1133`	`1134`	`if (arg_count)`
`1134`	`1135`	`max_length= args[0]->max_length;`
`1135`	`1136`	`}`