Merge mysql.com:/home/gluh/MySQL/Merge/5.0-opt

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt


mysql-test/r/func_gconcat.result:
  Auto merged
mysql-test/t/func_gconcat.test:
  Auto merged
sql/item_sum.cc:
  Auto merged

3 files changed, 19 insertions, 1 deletions

diff --git a/mysql-test/r/func_gconcat.result b/mysql-test/r/func_gconcat.result
index 7ae7806baea..d257e526abf 100644
--- a/mysql-test/r/func_gconcat.result
+++ b/mysql-test/r/func_gconcat.result
@@ -867,4 +867,13 @@ select group_concat(distinct a, c order by a desc, c desc) from t1;
 group_concat(distinct a, c order by a desc, c desc)
 31,11,10,01,00
 drop table t1;
+create table t1 (f1 char(20));
+insert into t1 values (''),('');
+select group_concat(distinct f1) from t1;
+group_concat(distinct f1)
+
+select group_concat(f1) from t1;
+group_concat(f1)
+,
+drop table t1;
 End of 5.0 tests
diff --git a/mysql-test/t/func_gconcat.test b/mysql-test/t/func_gconcat.test
index 4c5dd6467bd..322be2b7b8e 100644
--- a/mysql-test/t/func_gconcat.test
+++ b/mysql-test/t/func_gconcat.test
@@ -590,4 +590,13 @@ select group_concat(distinct a, c order by a desc, c desc) from t1;
 drop table t1;
 
 
+#
+# Bug#30897 GROUP_CONCAT returns extra comma on empty fields
+#
+create table t1 (f1 char(20));
+insert into t1 values (''),('');
+select group_concat(distinct f1) from t1;
+select group_concat(f1) from t1;
+drop table t1;
+
 --echo End of 5.0 tests
diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index 0e1daadd8e7..a7574cf4d60 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -3427,7 +3427,7 @@ String* Item_func_group_concat::val_str(String* str)
   DBUG_ASSERT(fixed == 1);
   if (null_value)
     return 0;
-  if (!result.length() && tree)
+  if (no_appended && tree)
     /* Tree is used for sorting as in ORDER BY */
     tree_walk(tree, (tree_walk_action)&dump_leaf_key, (void*)this,
               left_root_right);