Bug #39283: Date returned as VARBINARY to client for queries

            with COALESCE and JOIN

The server returned to a client the VARBINARY column type
instead of the DATE type for a result of the COALESCE,
IFNULL, IF, CASE, GREATEST or LEAST functions if that result
was filesorted in an anonymous temporary table during
the query execution.

For example:
  SELECT COALESCE(t1.date1, t2.date2) AS result
    FROM t1 JOIN t2 ON t1.id = t2.id ORDER BY result;


To create a column of various date/time types in a
temporary table the create_tmp_field_from_item() function
uses the Item::tmp_table_field_from_field_type() method
call. However, fields of the MYSQL_TYPE_NEWDATE type were
missed there, and the VARBINARY columns were created
by default.
Necessary condition has been added.

mysql-test/r/metadata.result

@@ -181,4 +181,21 @@ c1	c2
 3	3
 DROP VIEW v1,v2;
 DROP TABLE t1,t2;
+CREATE TABLE t1 (i INT, d DATE);
+INSERT INTO t1 VALUES (1, '2008-01-01'), (2, '2008-01-02'), (3, '2008-01-03');
+SELECT COALESCE(d, d), IFNULL(d, d), IF(i, d, d),
+CASE i WHEN i THEN d ELSE d END, GREATEST(d, d), LEAST(d, d)
+FROM t1 ORDER BY RAND();
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+2008-01-01	2008-01-01	2008-01-01	2008-01-01	2008-01-01	2008-01-01
+2008-01-02	2008-01-02	2008-01-02	2008-01-02	2008-01-02	2008-01-02
+2008-01-03	2008-01-03	2008-01-03	2008-01-03	2008-01-03	2008-01-03
+COALESCE(d, d)	IFNULL(d, d)	IF(i, d, d)	CASE i WHEN i THEN d ELSE d END	GREATEST(d, d)	LEAST(d, d)
+def				CASE i WHEN i THEN d ELSE d END	CASE i WHEN i THEN d ELSE d END	10	10	10	Y	128	0	63
+def				COALESCE(d, d)	COALESCE(d, d)	10	10	10	Y	128	0	63
+def				GREATEST(d, d)	GREATEST(d, d)	10	10	10	Y	128	0	63
+def				IF(i, d, d)	IF(i, d, d)	10	10	10	Y	128	0	63
+def				IFNULL(d, d)	IFNULL(d, d)	10	10	10	Y	128	0	63
+def				LEAST(d, d)	LEAST(d, d)	10	10	10	Y	128	0	63
+DROP TABLE t1;
 End of 5.0 tests

mysql-test/t/metadata.test

@@ -112,4 +112,21 @@ SELECT v1.c1, v2.c2 FROM v1 JOIN v2 ON c1=c2 GROUP BY v1.c1 ORDER BY v2.c2;
 DROP VIEW v1,v2;
 DROP TABLE t1,t2;
 
+#
+# Bug #39283: Date returned as VARBINARY to client for queries
+#             with COALESCE and JOIN
+#
+
+CREATE TABLE t1 (i INT, d DATE);
+INSERT INTO t1 VALUES (1, '2008-01-01'), (2, '2008-01-02'), (3, '2008-01-03');
+
+--enable_metadata
+--sorted_result
+SELECT COALESCE(d, d), IFNULL(d, d), IF(i, d, d),
+       CASE i WHEN i THEN d ELSE d END, GREATEST(d, d), LEAST(d, d)
+  FROM t1 ORDER BY RAND(); # force filesort
+--disable_metadata
+
+DROP TABLE t1;
+
 --echo End of 5.0 tests

sql/sql_select.cc

@@ -8964,6 +8964,7 @@ static Field *create_tmp_field_from_item(THD *thd, Item *item, TABLE *table,
     */
     if ((type= item->field_type()) == MYSQL_TYPE_DATETIME ||
         type == MYSQL_TYPE_TIME || type == MYSQL_TYPE_DATE ||
+        type == MYSQL_TYPE_NEWDATE ||
         type == MYSQL_TYPE_TIMESTAMP || type == MYSQL_TYPE_GEOMETRY)
       new_field= item->tmp_table_field_from_field_type(table);
     /*