A fix for Bug#14897 "ResultSet.getString("table.column") sometimes

doesn't find the column"

When a user was using 4.1 tables with VARCHAR column and 5.0 server
and a query that used a temporary table to resolve itself, the
table metadata for the varchar column sent to client was incorrect:
MYSQL_FIELD::table member was empty.

The bug was caused by implicit "upgrade" from old VARCHAR to new
VARCHAR hard-coded in Field::new_field, which did not preserve
the information about the original table. Thus, the field metadata
of the "upgraded" field pointed to an auxiliary temporary table
created for query execution.

The fix is to copy the pointer to the original table to the new field.

mysql-test/r/type_varchar.result

@@ -422,3 +422,34 @@ DROP TABLE IF EXISTS t1;
 CREATE TABLE t1(f1 CHAR(100) DEFAULT 'test');
 INSERT INTO t1 VALUES(SUBSTR(f1, 1, 3));
 DROP TABLE IF EXISTS t1;
+drop table if exists t1, t2, t3;
+create table t3 (
+id int(11),
+en varchar(255) character set utf8,
+cz varchar(255) character set utf8
+);
+truncate table t3;
+insert into t3 (id, en, cz) values 
+(1,'en string 1','cz string 1'),
+(2,'en string 2','cz string 2'),
+(3,'en string 3','cz string 3');
+create table t1 ( 
+id int(11),
+name_id int(11)
+);
+insert into t1 (id, name_id) values (1,1), (2,3), (3,3);
+create table t2 (id int(11));
+insert into t2 (id) values (1), (2), (3);
+select t1.*, t2.id, t3.en, t3.cz from t1 left join t2 on t1.id=t2.id
+left join t3 on t1.id=t3.id order by t3.id;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	t1	id	id	3	11	1	Y	32768	0	63
+def	test	t1	t1	name_id	name_id	3	11	1	Y	32768	0	63
+def	test	t2	t2	id	id	3	11	1	Y	32768	0	63
+def	test	t3	t3	en	en	253	255	11	Y	0	0	8
+def	test	t3	t3	cz	cz	253	255	11	Y	0	0	8
+id	name_id	id	en	cz
+1	1	1	en string 1	cz string 1
+2	3	2	en string 2	cz string 2
+3	3	3	en string 3	cz string 3
+drop table t1, t2, t3;

mysql-test/t/type_varchar.test

@@ -146,3 +146,44 @@ DROP TABLE IF EXISTS t1;
 CREATE TABLE t1(f1 CHAR(100) DEFAULT 'test');
 INSERT INTO t1 VALUES(SUBSTR(f1, 1, 3));
 DROP TABLE IF EXISTS t1;
+
+#
+# Bug#14897 "ResultSet.getString("table.column") sometimes doesn't find the
+# column"
+# Test that after upgrading an old 4.1 VARCHAR column to 5.0 VARCHAR we preserve
+# the original column metadata.
+#
+--disable_warnings
+drop table if exists t1, t2, t3;
+--enable_warnings
+
+create table t3 (
+  id int(11),
+  en varchar(255) character set utf8,
+  cz varchar(255) character set utf8
+);
+system cp $MYSQL_TEST_DIR/std_data/14897.frm $MYSQLTEST_VARDIR/master-data/test/t3.frm;
+truncate table t3;
+insert into t3 (id, en, cz) values 
+(1,'en string 1','cz string 1'),
+(2,'en string 2','cz string 2'),
+(3,'en string 3','cz string 3');
+
+create table t1 ( 
+  id int(11),
+  name_id int(11)
+);
+insert into t1 (id, name_id) values (1,1), (2,3), (3,3);
+
+create table t2 (id int(11));
+insert into t2 (id) values (1), (2), (3);
+
+# max_length is different for varchar fields in ps-protocol and we can't 
+# replace a single metadata column, disable PS protocol
+--disable_ps_protocol
+--enable_metadata
+select t1.*, t2.id, t3.en, t3.cz from t1 left join t2 on t1.id=t2.id
+left join t3 on t1.id=t3.id order by t3.id;
+--disable_metadata
+--enable_ps_protocol
+drop table t1, t2, t3;

sql/field.cc

@@ -6154,15 +6154,26 @@ Field *Field_string::new_field(MEM_ROOT *root, struct st_table *new_table,
   Field *new_field;
 
   if (type() != MYSQL_TYPE_VAR_STRING || keep_type)
-    return Field::new_field(root, new_table, keep_type);
+    new_field= Field::new_field(root, new_table, keep_type);
+  else
+  {
 
-  /*
-    Old VARCHAR field which should be modified to a VARCHAR on copy
-    This is done to ensure that ALTER TABLE will convert old VARCHAR fields
-    to now VARCHAR fields.
-  */
-  return new Field_varstring(field_length, maybe_null(),
-                             field_name, new_table, charset());
+    /*
+      Old VARCHAR field which should be modified to a VARCHAR on copy
+      This is done to ensure that ALTER TABLE will convert old VARCHAR fields
+      to now VARCHAR fields.
+    */
+    new_field= new Field_varstring(field_length, maybe_null(),
+                                   field_name, new_table, charset());
+    /*
+      Normally orig_table is different from table only if field was created
+      via ::new_field.  Here we alter the type of field, so ::new_field is
+      not applicable. But we still need to preserve the original field
+      metadata for the client-server protocol.
+    */
+    new_field->orig_table= orig_table;
+  }
+  return new_field;
 }
 
 /****************************************************************************