bk commit into 5.0 tree (gluh:1.2555) BUG#30897

[gluh]

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ChangeSet@stripped, 2007-10-29 14:53:10+04:00, gluh@stripped +3 -0
  Bug#30897 GROUP_CONCAT returns extra comma on empty fields
  The fix is a copy of Martin Friebe's suggestion.
  added testing for no_appended which will be false if anything,
  including the empty string is in result

  mysql-test/r/func_gconcat.result@stripped, 2007-10-29 14:53:09+04:00, gluh@stripped +9 -0
    test result

  mysql-test/t/func_gconcat.test@stripped, 2007-10-29 14:53:09+04:00, gluh@stripped +9 -0
    test case

  sql/item_sum.cc@stripped, 2007-10-29 14:53:09+04:00, gluh@stripped +1 -1
    added testing for no_appended which will be False if anything,
    including the empty string is in result

diff -Nrup a/mysql-test/r/func_gconcat.result b/mysql-test/r/func_gconcat.result
--- a/mysql-test/r/func_gconcat.result	2007-10-11 17:20:32 +05:00
+++ b/mysql-test/r/func_gconcat.result	2007-10-29 14:53:09 +04:00
@@ -861,4 +861,13 @@ select group_concat(distinct a, c order 
 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 -Nrup a/mysql-test/t/func_gconcat.test b/mysql-test/t/func_gconcat.test
--- a/mysql-test/t/func_gconcat.test	2007-10-11 17:20:32 +05:00
+++ b/mysql-test/t/func_gconcat.test	2007-10-29 14:53:09 +04:00
@@ -590,4 +590,13 @@ select group_concat(distinct a, c order 
 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 -Nrup a/sql/item_sum.cc b/sql/item_sum.cc
--- a/sql/item_sum.cc	2007-10-23 18:48:55 +05:00
+++ b/sql/item_sum.cc	2007-10-29 14:53:09 +04:00
@@ -3406,7 +3406,7 @@ String* Item_func_group_concat::val_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);