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Bug #49480: WHERE using YEAR columns returns unexpected results

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A few problems were found in the fix for bug 43668:
1) Comparison of the YEAR column with NULL always returned TRUE;
2) Comparison of the YEAR column with constants always returned
   unpredictable result;
3) Unnecessary conversion warnings when comparing a non-integer
   constant with a NULL value in the YEAR column;

The problems described above have been resolved with an
exception: zero (i.e. invalid) YEAR column value comparison
with 00 or 2000 still fail (it is not a regression and it was
not a regression), so MIN/MAX on YEAR column containing zero
value still fail.


mysql-test/r/type_year.result:
  Test case for bug #49480.
mysql-test/t/type_year.test:
  Test case for bug #49480.
sql/item_cmpfunc.cc:
  - The get_year_value() function has been modified to make its
    return value compatible with the get_datetime_value() return
    value (i.e. to convert numeric values into the YYYY0000000000
    (YYYY-00-00 00:00:00) form.
  
  - The Arg_comparator::set_cmp_func method has been modified to
    use the get_year_value function if get_datetime_value() is not
    applicable.
    From now only 2 cases have a special processing there:
    * both comparing items have MYSQL_TYPE_YEAR field type
            or
    * one item have is MYSQL_TYPE_YEAR and other one is
      is_datetime()-compliant.
  
  - New helper function try_year_cmp_func() has been
    added for the better code readability to call from
    Arg_comparator::set_cmp_func().
  
  - The Arg_comparator::compare_year method has been removed
    since get_year_value() is compatible with the old
    Arg_comparator::compare_datetime method that doesn't have
    problems #1-#3 (see whole patch entry commentary).
sql/item_cmpfunc.h:
  - New helper function try_year_cmp_func() has been
    added for the better code readability to call from
    Arg_comparator::set_cmp_func().
  
  - Unnecessary Arg_comparator::year_as_datetime and
    Arg_comparator::compare_year() declarations have been
    removed.
This commit is contained in:
Gleb Shchepa 2009-12-10 10:05:44 +04:00
commit 3246383301
4 changed files with 421 additions and 102 deletions
Download patch file Download diff file Expand all files Collapse all files

144
sql/item_cmpfunc.cc
View file

@ -956,40 +956,9 @@ int Arg_comparator::set_cmp_func(Item_result_field *owner_arg,
if (agg_item_set_converter(coll, owner->func_name(),
b, 1, MY_COLL_CMP_CONV, 1))
return 1;
} else if (type != ROW_RESULT && ((*a)->field_type() == MYSQL_TYPE_YEAR ||
(*b)->field_type() == MYSQL_TYPE_YEAR))
{
is_nulls_eq= is_owner_equal_func();
year_as_datetime= FALSE;
if ((*a)->is_datetime())
{
year_as_datetime= TRUE;
get_value_a_func= &get_datetime_value;
} else if ((*a)->field_type() == MYSQL_TYPE_YEAR)
get_value_a_func= &get_year_value;
else
{
/*
Because convert_constant_item is called only for EXECUTE in PS mode
the value of get_value_x_func set in PREPARE might be not
valid for EXECUTE.
*/
get_value_a_func= NULL;
}
if ((*b)->is_datetime())
{
year_as_datetime= TRUE;
get_value_b_func= &get_datetime_value;
} else if ((*b)->field_type() == MYSQL_TYPE_YEAR)
get_value_b_func= &get_year_value;
else
get_value_b_func= NULL;
func= &Arg_comparator::compare_year;
return 0;
}
else if (try_year_cmp_func(type))
return 0;
a= cache_converted_constant(thd, a, &a_cache, type);
b= cache_converted_constant(thd, b, &b_cache, type);
@ -997,6 +966,45 @@ int Arg_comparator::set_cmp_func(Item_result_field *owner_arg,
}
/*
Helper function to call from Arg_comparator::set_cmp_func()
*/
bool Arg_comparator::try_year_cmp_func(Item_result type)
{
if (type == ROW_RESULT)
return FALSE;
bool a_is_year= (*a)->field_type() == MYSQL_TYPE_YEAR;
bool b_is_year= (*b)->field_type() == MYSQL_TYPE_YEAR;
if (!a_is_year && !b_is_year)
return FALSE;
if (a_is_year && b_is_year)
{
get_value_a_func= &get_year_value;
get_value_b_func= &get_year_value;
}
else if (a_is_year && (*b)->is_datetime())
{
get_value_a_func= &get_year_value;
get_value_b_func= &get_datetime_value;
}
else if (b_is_year && (*a)->is_datetime())
{
get_value_b_func= &get_year_value;
get_value_a_func= &get_datetime_value;
}
else
return FALSE;
is_nulls_eq= is_owner_equal_func();
func= &Arg_comparator::compare_datetime;
return TRUE;
}
/**
Convert and cache a constant.
@ -1147,7 +1155,7 @@ get_datetime_value(THD *thd, Item ***item_arg, Item **cache_arg,
/*
Retrieves YEAR value of 19XX form from given item.
Retrieves YEAR value of 19XX-00-00 00:00:00 form from given item.
SYNOPSIS
get_year_value()
@ -1159,7 +1167,9 @@ get_datetime_value(THD *thd, Item ***item_arg, Item **cache_arg,
DESCRIPTION
Retrieves the YEAR value of 19XX form from given item for comparison by the
compare_year() function.
compare_datetime() function.
Converts year to DATETIME of form YYYY-00-00 00:00:00 for the compatibility
with the get_datetime_value function result.
RETURN
obtained value
@ -1186,6 +1196,9 @@ get_year_value(THD *thd, Item ***item_arg, Item **cache_arg,
if (value <= 1900)
value+= 1900;
/* Convert year to DATETIME of form YYYY-00-00 00:00:00 (YYYY0000000000). */
value*= 10000000000LL;
return value;
}
@ -1615,67 +1628,6 @@ int Arg_comparator::compare_e_row()
}
/**
Compare values as YEAR.
@details
Compare items as YEAR for EQUAL_FUNC and for other comparison functions.
The YEAR values of form 19XX are obtained with help of the get_year_value()
function.
If one of arguments is of DATE/DATETIME type its value is obtained
with help of the get_datetime_value function. In this case YEAR values
prior to comparison are converted to the ulonglong YYYY-00-00 00:00:00
DATETIME form.
If an argument type neither YEAR nor DATE/DATEIME then val_int function
is used to obtain value for comparison.
RETURN
If is_nulls_eq is TRUE:
1 if items are equal or both are null
0 otherwise
If is_nulls_eq is FALSE:
-1 a < b
0 a == b or at least one of items is null
1 a > b
See the table:
is_nulls_eq | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 |
a_is_null | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 |
b_is_null | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 0 |
result | 1 | 0 | 0 |0/1| 0 | 0 | 0 |-1/0/1|
*/
int Arg_comparator::compare_year()
{
bool a_is_null, b_is_null;
ulonglong val1= get_value_a_func ?
(*get_value_a_func)(thd, &a, &a_cache, *b, &a_is_null) :
(*a)->val_int();
ulonglong val2= get_value_b_func ?
(*get_value_b_func)(thd, &b, &b_cache, *a, &b_is_null) :
(*b)->val_int();
if (!(*a)->null_value)
{
if (!(*b)->null_value)
{
if (set_null)
owner->null_value= 0;
/* Convert year to DATETIME of form YYYY-00-00 00:00:00 when necessary. */
if((*a)->field_type() == MYSQL_TYPE_YEAR && year_as_datetime)
val1*= 10000000000LL;
if((*b)->field_type() == MYSQL_TYPE_YEAR && year_as_datetime)
val2*= 10000000000LL;
if (val1 < val2) return is_nulls_eq ? 0 : -1;
if (val1 == val2) return is_nulls_eq ? 1 : 0;
return is_nulls_eq ? 0 : 1;
}
}
if (set_null)
owner->null_value= is_nulls_eq ? 0 : 1;
return (is_nulls_eq && (*a)->null_value == (*b)->null_value) ? 1 : 0;
}
void Item_func_truth::fix_length_and_dec()
{
maybe_null= 0;