Bug#28778: Wrong result of BETWEEN when comparing a DATETIME field with an

integer constants.

This bug is introduced by the fix for bug#16377. Before the fix the 
Item_func_between::fix_length_and_dec method converted the second and third
arguments to the type of the first argument if they were constant and the first
argument is of the DATE/DATETIME type. That approach worked well for integer
constants and sometimes produced bad result for string constants. The fix for
the bug#16377 wrongly removed that code at all and as a result of this the
comparison of a DATETIME field and an integer constant was carried out in a
wrong way and sometimes led to wrong result sets.

Now the Item_func_between::fix_length_and_dec method converts the second and
third arguments to the type of the first argument if they are constant, the
first argument is of the DATE/DATETIME type and the DATETIME comparator isn't
applicable.

mysql-test/r/type_datetime.result

@@ -411,3 +411,19 @@ if(@bug28261 = f1, '', @bug28261:= f1)
 2001-01-01
 2002-02-02
 drop table t1;
+create table t1(f1 datetime);
+insert into t1 values('2001-01-01'),('2002-02-02');
+select * from t1 where f1 between 20020101 and 20070101000000;
+f1
+2002-02-02 00:00:00
+select * from t1 where f1 between 2002010 and 20070101000000;
+f1
+2001-01-01 00:00:00
+2002-02-02 00:00:00
+Warnings:
+Warning	1292	Incorrect datetime value: '2002010' for column 'f1' at row 1
+select * from t1 where f1 between 20020101 and 2007010100000;
+f1
+Warnings:
+Warning	1292	Incorrect datetime value: '2007010100000' for column 'f1' at row 1
+drop table t1;

mysql-test/t/type_datetime.test

@@ -271,3 +271,14 @@ select if(@bug28261 = f1, '', @bug28261:= f1) from t1;
 select if(@bug28261 = f1, '', @bug28261:= f1) from t1;
 select if(@bug28261 = f1, '', @bug28261:= f1) from t1;
 drop table t1;
+
+#
+# Bug#28778: Wrong result of BETWEEN when comparing a DATETIME field with an
+#            integer constants.
+#
+create table t1(f1 datetime);
+insert into t1 values('2001-01-01'),('2002-02-02');
+select * from t1 where f1 between 20020101 and 20070101000000;
+select * from t1 where f1 between 2002010 and 20070101000000;
+select * from t1 where f1 between 20020101 and 2007010100000;
+drop table t1;

sql/item_cmpfunc.cc

@@ -1755,6 +1755,23 @@ void Item_func_between::fix_length_and_dec()
     ge_cmp.set_datetime_cmp_func(args, args + 1);
     le_cmp.set_datetime_cmp_func(args, args + 2);
   }
+  else if (args[0]->real_item()->type() == FIELD_ITEM &&
+           thd->lex->sql_command != SQLCOM_CREATE_VIEW &&
+           thd->lex->sql_command != SQLCOM_SHOW_CREATE)
+  {
+    Field *field=((Item_field*) (args[0]->real_item()))->field;
+    if (field->can_be_compared_as_longlong())
+    {
+      /*
+        The following can't be recoded with || as convert_constant_item
+        changes the argument
+      */
+      if (convert_constant_item(thd, field,&args[1]))
+        cmp_type=INT_RESULT;			// Works for all types.
+      if (convert_constant_item(thd, field,&args[2]))
+        cmp_type=INT_RESULT;			// Works for all types.
+    }
+  }
 }