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BUG#25575: ERROR 1052 (Column in from clause is ambiguous) with sub-join

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Two problems here:

 Problem 1:

 While constructing the join columns list the optimizer does as follows:
  1. Sets the join_using_fields/natural_join members of the right JOIN 
   operand.
  2. Makes a "table reference" (TABLE_LIST) to parent the two tables.
  3. Assigns the join_using_fields/is_natural_join of the wrapper table
   using join_using_fields/natural_join of the rightmost table
  4. Sets join_using_fields to NULL for the right JOIN operand.
  5. Passes the parent table up to the same procedure on the upper 
   level.

 Step 1 overrides the the join_using_fields that are set for a nested 
 join wrapping table in step 4.
 Fixed by making a designated variable SELECT_LEX::prev_join_using to 
 pass the data from step 1 to step 4 without destroying the wrapping 
 table data.

 Problem 2:

 The optimizer checks for ambiguous columns while transforming 
 NATURAL JOIN/JOIN USING to JOIN ON. While doing that there was no
 distinction between columns that are used in the generated join
 condition (where ambiguity can be checked) and the other columns
 (where ambiguity can be checked only when resolving references
 coming from outside the JOIN construct itself).
 Fixed by allowing the non-USING columns to be present in multiple 
 copies in both sides of the join and moving the ambiguity check 
 to the place where unqualified references to the join columns are
 resolved (find_field_in_natural_join()).
This commit is contained in:
gkodinov/kgeorge@macbook.gmz
2007-01-31 16:04:38 +02:00
parent f3b3f1ef73
commit 16d2d68257
8 changed files with 140 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

51
sql/sql_base.cc
View File

@ -2945,7 +2945,7 @@ find_field_in_natural_join(THD *thd, TABLE_LIST *table_ref, const char *name,
{
List_iterator_fast<Natural_join_column>
field_it(*(table_ref->join_columns));
Natural_join_column *nj_col;
Natural_join_column *nj_col, *curr_nj_col;
Field *found_field;
Query_arena *arena, backup;
DBUG_ENTER("find_field_in_natural_join");
@ -2956,14 +2956,21 @@ find_field_in_natural_join(THD *thd, TABLE_LIST *table_ref, const char *name,
LINT_INIT(found_field);
for (;;)
for (nj_col= NULL, curr_nj_col= field_it++; curr_nj_col;
curr_nj_col= field_it++)
{
if (!(nj_col= field_it++))
DBUG_RETURN(NULL);
if (!my_strcasecmp(system_charset_info, nj_col->name(), name))
break;
if (!my_strcasecmp(system_charset_info, curr_nj_col->name(), name))
{
if (nj_col)
{
my_error(ER_NON_UNIQ_ERROR, MYF(0), name, thd->where);
DBUG_RETURN(NULL);
}
nj_col= curr_nj_col;
}
}
if (!nj_col)
DBUG_RETURN(NULL);
if (nj_col->view_field)
{
@ -3774,9 +3781,16 @@ mark_common_columns(THD *thd, TABLE_LIST *table_ref_1, TABLE_LIST *table_ref_2,
{
bool found= FALSE;
const char *field_name_1;
/* true if field_name_1 is a member of using_fields */
bool is_using_column_1;
if (!(nj_col_1= it_1.get_or_create_column_ref(leaf_1)))
goto err;
field_name_1= nj_col_1->name();
is_using_column_1= using_fields &&
test_if_string_in_list(field_name_1, using_fields);
DBUG_PRINT ("info", ("field_name_1=%s.%s",
nj_col_1->table_name() ? nj_col_1->table_name() : "",
field_name_1));
/*
Find a field with the same name in table_ref_2.
@ -3793,6 +3807,10 @@ mark_common_columns(THD *thd, TABLE_LIST *table_ref_1, TABLE_LIST *table_ref_2,
if (!(cur_nj_col_2= it_2.get_or_create_column_ref(leaf_2)))
goto err;
cur_field_name_2= cur_nj_col_2->name();
DBUG_PRINT ("info", ("cur_field_name_2=%s.%s",
cur_nj_col_2->table_name() ?
cur_nj_col_2->table_name() : "",
cur_field_name_2));
/*
Compare the two columns and check for duplicate common fields.
@ -3800,10 +3818,16 @@ mark_common_columns(THD *thd, TABLE_LIST *table_ref_1, TABLE_LIST *table_ref_2,
table_ref_2 (then found == TRUE), or if a field in table_ref_2
was already matched by some previous field in table_ref_1
(then cur_nj_col_2->is_common == TRUE).
Note that it is too early to check the columns outside of the
USING list for ambiguity because they are not actually "referenced"
here. These columns must be checked only on unqualified reference
by name (e.g. in SELECT list).
*/
if (!my_strcasecmp(system_charset_info, field_name_1, cur_field_name_2))
{
if (found || cur_nj_col_2->is_common)
DBUG_PRINT ("info", ("match c1.is_common=%d", nj_col_1->is_common));
if (cur_nj_col_2->is_common ||
(found && (!using_fields || is_using_column_1)))
{
my_error(ER_NON_UNIQ_ERROR, MYF(0), field_name_1, thd->where);
goto err;
@ -3829,9 +3853,7 @@ mark_common_columns(THD *thd, TABLE_LIST *table_ref_1, TABLE_LIST *table_ref_2,
clause (if present), mark them as common fields, and add a new
equi-join condition to the ON clause.
*/
if (nj_col_2 &&
(!using_fields ||
test_if_string_in_list(field_name_1, using_fields)))
if (nj_col_2 && (!using_fields ||is_using_column_1))
{
Item *item_1= nj_col_1->create_item(thd);
Item *item_2= nj_col_2->create_item(thd);
@ -3886,6 +3908,13 @@ mark_common_columns(THD *thd, TABLE_LIST *table_ref_1, TABLE_LIST *table_ref_2,
eq_cond);
nj_col_1->is_common= nj_col_2->is_common= TRUE;
DBUG_PRINT ("info", ("%s.%s and %s.%s are common",
nj_col_1->table_name() ?
nj_col_1->table_name() : "",
nj_col_1->name(),
nj_col_2->table_name() ?
nj_col_2->table_name() : "",
nj_col_2->name()));
if (field_1)
{