• unknown's avatar
    Fix bug #12861 client hang with group_concat insubquery FROM DUAL. · fc45b816
    unknown authored
    Item_func_group_concat::fix_fields() set maybe_null flag to 0, and set it to
    1 only if some of it's arguments may be null. When used in subquery in tmp 
    table created field which can't be null. When no data retireved result field
    have to be set to null and error mentioned in bug report occurs. Also this 
    bug can occur if selecting from not null field in empty table.
    
    Function group_concat now marked maybe_null from the very beginning not only
    if some of it's argument may be null.
    
    
    sql/item_sum.cc:
      Fix bug #12861 client hang with group_concat insubquery FROM DUAL.
    mysql-test/r/func_gconcat.result:
      Test case for bug #12861 client hang with group_concat insubquery FROM DUAL.
    mysql-test/t/func_gconcat.test:
      Test case for bug #12861 client hang with group_concat insubquery FROM DUAL.
    fc45b816
func_gconcat.test 13.1 KB