Merge ibabaev@bk-internal.mysql.com:/home/bk/mysql-5.0-opt

into  olga.mysql.com:/home/igor/mysql-5.0-opt

mysql-test/r/information_schema.result

@@ -1170,3 +1170,65 @@ f1()
 DROP FUNCTION f1;
 DROP PROCEDURE p1;
 DROP USER mysql_bug20230@localhost;
+SELECT t.table_name, c1.column_name
+FROM information_schema.tables t
+INNER JOIN
+information_schema.columns c1
+ON t.table_schema = c1.table_schema AND
+t.table_name = c1.table_name
+WHERE t.table_schema = 'information_schema' AND
+c1.ordinal_position =
+( SELECT COALESCE(MIN(c2.ordinal_position),1)
+FROM information_schema.columns c2
+WHERE c2.table_schema = t.table_schema AND
+c2.table_name = t.table_name AND
+c2.column_name LIKE '%SCHEMA%'
+        );
+table_name	column_name
+CHARACTER_SETS	CHARACTER_SET_NAME
+COLLATIONS	COLLATION_NAME
+COLLATION_CHARACTER_SET_APPLICABILITY	COLLATION_NAME
+COLUMNS	TABLE_SCHEMA
+COLUMN_PRIVILEGES	TABLE_SCHEMA
+KEY_COLUMN_USAGE	CONSTRAINT_SCHEMA
+ROUTINES	ROUTINE_SCHEMA
+SCHEMATA	SCHEMA_NAME
+SCHEMA_PRIVILEGES	TABLE_SCHEMA
+STATISTICS	TABLE_SCHEMA
+TABLES	TABLE_SCHEMA
+TABLE_CONSTRAINTS	CONSTRAINT_SCHEMA
+TABLE_PRIVILEGES	TABLE_SCHEMA
+TRIGGERS	TRIGGER_SCHEMA
+USER_PRIVILEGES	GRANTEE
+VIEWS	TABLE_SCHEMA
+SELECT t.table_name, c1.column_name
+FROM information_schema.tables t
+INNER JOIN
+information_schema.columns c1
+ON t.table_schema = c1.table_schema AND
+t.table_name = c1.table_name
+WHERE t.table_schema = 'information_schema' AND
+c1.ordinal_position =
+( SELECT COALESCE(MIN(c2.ordinal_position),1)
+FROM information_schema.columns c2
+WHERE c2.table_schema = 'information_schema' AND
+c2.table_name = t.table_name AND
+c2.column_name LIKE '%SCHEMA%'
+        );
+table_name	column_name
+CHARACTER_SETS	CHARACTER_SET_NAME
+COLLATIONS	COLLATION_NAME
+COLLATION_CHARACTER_SET_APPLICABILITY	COLLATION_NAME
+COLUMNS	TABLE_SCHEMA
+COLUMN_PRIVILEGES	TABLE_SCHEMA
+KEY_COLUMN_USAGE	CONSTRAINT_SCHEMA
+ROUTINES	ROUTINE_SCHEMA
+SCHEMATA	SCHEMA_NAME
+SCHEMA_PRIVILEGES	TABLE_SCHEMA
+STATISTICS	TABLE_SCHEMA
+TABLES	TABLE_SCHEMA
+TABLE_CONSTRAINTS	CONSTRAINT_SCHEMA
+TABLE_PRIVILEGES	TABLE_SCHEMA
+TRIGGERS	TRIGGER_SCHEMA
+USER_PRIVILEGES	GRANTEE
+VIEWS	TABLE_SCHEMA

mysql-test/t/information_schema.test

@@ -887,4 +887,37 @@ DROP FUNCTION f1;
 DROP PROCEDURE p1;
 DROP USER mysql_bug20230@localhost;
 
+#
+# Bug#18925: subqueries with MIN/MAX functions on INFORMARTION_SCHEMA 
+#
+
+SELECT t.table_name, c1.column_name
+  FROM information_schema.tables t
+       INNER JOIN
+       information_schema.columns c1
+       ON t.table_schema = c1.table_schema AND
+          t.table_name = c1.table_name
+  WHERE t.table_schema = 'information_schema' AND
+        c1.ordinal_position =
+        ( SELECT COALESCE(MIN(c2.ordinal_position),1)
+            FROM information_schema.columns c2
+            WHERE c2.table_schema = t.table_schema AND
+                  c2.table_name = t.table_name AND
+                  c2.column_name LIKE '%SCHEMA%'
+        );
+SELECT t.table_name, c1.column_name
+  FROM information_schema.tables t
+       INNER JOIN
+       information_schema.columns c1
+       ON t.table_schema = c1.table_schema AND
+          t.table_name = c1.table_name
+  WHERE t.table_schema = 'information_schema' AND
+        c1.ordinal_position =
+        ( SELECT COALESCE(MIN(c2.ordinal_position),1)
+            FROM information_schema.columns c2
+            WHERE c2.table_schema = 'information_schema' AND
+                  c2.table_name = t.table_name AND
+                  c2.column_name LIKE '%SCHEMA%'
+        );
+
 # End of 5.0 tests.

sql/sql_show.cc

@@ -3963,6 +3963,7 @@ bool get_schema_tables_result(JOIN *join)
         table_list->table->file->delete_all_rows();
         free_io_cache(table_list->table);
         filesort_free_buffers(table_list->table);
+        table_list->table->null_row= 0;
       }
       else
         table_list->table->file->records= 0;