bugfix: allow dropping a constraint and a column together

post-fix for 04b288ae

mysql-test/r/alter_table.result

@@ -2228,12 +2228,11 @@ alter table t1 drop column a;
 ERROR 42S22: Unknown column 'a' in 'CHECK'
 alter table t1 drop column b, add column b bigint first;
 ERROR 42S22: Unknown column 'b' in 'CHECK'
+alter table t1 drop column a, drop constraint constraint_1;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `a` int(11) DEFAULT NULL,
-  `b` int(11) DEFAULT NULL,
-  CONSTRAINT `CONSTRAINT_1` CHECK (`a` > `b`)
+  `b` int(11) DEFAULT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 create table t1 (a int, b int, check(a>0));
@@ -2265,12 +2264,11 @@ drop table t1;
 create table t1 (a int, b int, c int, unique(a,b));
 alter table t1 drop column a;
 ERROR 42000: Key column 'a' doesn't exist in table
+alter table t1 drop column a, drop index a;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `a` int(11) DEFAULT NULL,
   `b` int(11) DEFAULT NULL,
-  `c` int(11) DEFAULT NULL,
-  UNIQUE KEY `a` (`a`,`b`)
+  `c` int(11) DEFAULT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;

mysql-test/t/alter_table.test

@@ -1852,6 +1852,7 @@ create table t1 (a int, b int, check(a>b));
 alter table t1 drop column a;
 --error ER_BAD_FIELD_ERROR
 alter table t1 drop column b, add column b bigint first;
+alter table t1 drop column a, drop constraint constraint_1;
 show create table t1;
 drop table t1;
 
@@ -1873,5 +1874,6 @@ drop table t1;
 create table t1 (a int, b int, c int, unique(a,b));
 --error ER_KEY_COLUMN_DOES_NOT_EXITS
 alter table t1 drop column a;
+alter table t1 drop column a, drop index a;
 show create table t1;
 drop table t1;

sql/sql_table.cc

@@ -8041,7 +8041,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
         }
       }
       /* see if the constraint depends on *only* on dropped fields */
-      if (dropped_fields)
+      if (!drop && dropped_fields)
       {
         table->default_column_bitmaps();
         bitmap_clear_all(table->read_set);