When compiling GROUP BY Item_ref instances are dereferenced in
setup_copy_fields(), i.e. replaced with the corresponding Item_field
(if they point to one) or Item_copy_string for the other cases.
Since the Item_ref (in the Item_field case) is no longer used the information
about the aliases stored in it is lost.
Fixed by preserving the column, table and DB alias on dereferencing Item_ref
The problem was that any VIEW columns had always implicit derivation.
Fix: derivation is now copied from the original expression
given in VIEW definition.
For example:
- a VIEW column which comes from a string constant
in CREATE VIEW definition have now coercible derivation.
- a VIEW column having COLLATE clause
in CREATE VIEW definition have now explicit derivation.
The parser is allocating Item_field for references by name in ORDER BY
expressions. Such expressions however may point not only to Item_field
in the select list (or to a table column) but also to an arbitrary Item.
This causes Item_field::fix_fields to throw an error about missing
column.
The fix substitutes Item_field for the reference with an Item_ref when
not pointing to Item_field.
select OK.
The SQL parser was using Item::name to transfer user defined function attributes
to the user defined function (udf). It was not distinguishing between user defined
function call arguments and stored procedure call arguments. Setting Item::name
was causing Item_ref::print() method to print the argument as quoted identifiers
and caused views that reference aggregate functions as udf call arguments (and
rely on Item::print() for the text of the view to store) to throw an undefined
identifier error.
Overloaded Item_ref::print to print aggregate functions as such when printing
the references to aggregate functions taken out of context by split_sum_func2()
Fixed the parser to properly detect using AS clause in stored procedure arguments
as an error.
Fixed printing the arguments of udf call to print properly the udf attribute.
Re-execution of a parametrized prepared statement or a stored routine
with a SELECT that use LEFT JOIN with second table having only one row
could yield incorrect result.
The problem appeared only for left joins with second table having only
one row (aka const table) and equation conditions in ON or WHERE clauses
that depend on the argument passed. Once the condition was false for
second const table, a NULL row was created for it, and any field involved
got NULL-value flag, which then was never reset.
The cause of the problem was that Item_field::null_value could be set
without being reset for re-execution. The solution is to reset
Item_field::null_value in Item_field::cleanup().
result
The IN function aggregates result types of all expressions. It uses that
type in comparison of left expression and expressions in right part.
This approach works in most cases. But let's consider the case when the
right part contains both strings and integers. In that case this approach may
cause wrong results because all strings which do not start with a digit are
evaluated as 0.
CASE uses the same approach when a CASE expression is given thus it's also
affected.
The idea behind this fix is to make IN function to compare expressions with
different result types differently. For example a string in the left
part will be compared as string with strings specified in right part and
will be converted to real for comparison to int or real items in the right
part.
A new function called collect_cmp_types() is added. It collects different
result types for comparison of first item in the provided list with each
other item in the list.
The Item_func_in class now can refer up to 5 cmp_item objects: 1 for each
result type for comparison purposes. cmp_item objects are allocated according
to found result types. The comparison of the left expression with any
right part expression is now based only on result types of these expressions.
The Item_func_case class is modified in the similar way when a CASE
expression is specified. Now it can allocate up to 5 cmp_item objects
to compare CASE expression with WHEN expressions of different types.
The comparison of the CASE expression with any WHEN expression now based only
on result types of these expressions.
an ALL/ANY quantified subquery in HAVING.
The Item::split_sum_func2 method should not create Item_ref
for objects of any class derived from Item_subselect.
equal constant under any circumstances.
In fact this substitution can be allowed if the field is
not of a type string or if the field reference serves as
an argument of a comparison predicate.
A date can be represented as an int (like 20060101) and as a string (like
"2006.01.01"). When a DATE/TIME field is compared in one SELECT against both
representations the constant propagation mechanism leads to comparison
of DATE as a string and DATE as an int. In this example it compares 2006 and
20060101 integers. Obviously it fails comparison although they represents the
same date.
Now the Item_bool_func2::fix_length_and_dec() function sets the comparison
context for items being compared. I.e. if items compared as strings the
comparison context is STRING.
The constant propagation mechanism now doesn't mix items used in different
comparison contexts. The context check is done in the
Item_field::equal_fields_propagator() and in the change_cond_ref_to_const()
functions.
Also the better fix for bug 21159 is introduced.
There is an existing macros for initializing LEX_STRINGs
with constant strings -> C_STRING_WITH_LEN. Change existing code to use it.
(char *) STRING_WITH_LEN -> C_STRING_WITH_LEN
