From 94f75ffcce4daddfb709bd269fc90d1513833966 Mon Sep 17 00:00:00 2001 From: unknown Date: Tue, 11 Dec 2007 20:15:03 +0100 Subject: [PATCH 1/2] Bug#32848: Data type conversion bug in union subselects in MySQL 5.0.38 There were two problems when inferring the correct field types resulting from UNION queries. - If the type is NULL for all corresponding fields in the UNION, the resulting type would be NULL, while the type is BINARY(0) if there is just a single SELECT NULL. - If one SELECT in the UNION uses a subselect, a temporary table is created to represent the subselect, and the result type defaults to a STRING type, hiding the fact that the type was unknown(just a NULL value). Fixed by remembering whenever a field was created from a NULL value and pass type NULL to the type coercion if that is the case, and creating a string field as result of UNION only if the type would otherwise be NULL. mysql-test/r/union.result: Bug#32848: Test result mysql-test/t/union.test: Bug#32848: Test case sql/field.cc: Bug#32848: Initialization of new field sql/field.h: Bug#32848: New member to record when a field was created from a NULL value. sql/item.cc: Bug#32848: A field created from a NULL value will submit NULL as type to the type coercion procedure. If Item_type_holder has not inferred the correct type after processing all SELECTs in a UNION, a string field is created. sql/sql_select.cc: Bug#32848: Recording when a field is created from a NULL value. --- mysql-test/r/union.result | 24 ++++++++++++++++++++++++ mysql-test/t/union.test | 24 ++++++++++++++++++++++++ sql/field.cc | 3 ++- sql/field.h | 10 ++++++++++ sql/item.cc | 4 ++++ sql/sql_select.cc | 2 ++ 6 files changed, 66 insertions(+), 1 deletion(-) diff --git a/mysql-test/r/union.result b/mysql-test/r/union.result index efdd8195fb5..0b77459e02f 100644 --- a/mysql-test/r/union.result +++ b/mysql-test/r/union.result @@ -1389,4 +1389,28 @@ select @var; 1 (select 2) union (select 1 into @var); ERROR 42000: Result consisted of more than one row +CREATE TABLE t1 (a INT); +INSERT INTO t1 VALUES (1), (2), (3); +CREATE TABLE t2 SELECT * FROM (SELECT NULL) a UNION SELECT a FROM t1; +DESC t2; +Field Type Null Key Default Extra +NULL int(11) YES NULL +CREATE TABLE t3 SELECT a FROM t1 UNION SELECT * FROM (SELECT NULL) a; +DESC t3; +Field Type Null Key Default Extra +a int(11) YES NULL +CREATE TABLE t4 SELECT NULL; +DESC t4; +Field Type Null Key Default Extra +NULL binary(0) YES NULL +CREATE TABLE t5 SELECT NULL UNION SELECT NULL; +DESC t5; +Field Type Null Key Default Extra +NULL binary(0) YES NULL +CREATE TABLE t6 +SELECT * FROM (SELECT * FROM (SELECT NULL)a) b UNION SELECT a FROM t1; +DESC t6; +Field Type Null Key Default Extra +NULL int(11) YES NULL +DROP TABLE t1, t2, t3, t4, t5, t6; End of 5.0 tests diff --git a/mysql-test/t/union.test b/mysql-test/t/union.test index 22f09466b1c..84616aa281d 100644 --- a/mysql-test/t/union.test +++ b/mysql-test/t/union.test @@ -877,4 +877,28 @@ DROP TABLE t1; select @var; --error 1172 (select 2) union (select 1 into @var); + +# +# Bug#32848: Data type conversion bug in union subselects in MySQL 5.0.38 +# +CREATE TABLE t1 (a INT); +INSERT INTO t1 VALUES (1), (2), (3); + +CREATE TABLE t2 SELECT * FROM (SELECT NULL) a UNION SELECT a FROM t1; +DESC t2; + +CREATE TABLE t3 SELECT a FROM t1 UNION SELECT * FROM (SELECT NULL) a; +DESC t3; + +CREATE TABLE t4 SELECT NULL; +DESC t4; + +CREATE TABLE t5 SELECT NULL UNION SELECT NULL; +DESC t5; + +CREATE TABLE t6 +SELECT * FROM (SELECT * FROM (SELECT NULL)a) b UNION SELECT a FROM t1; +DESC t6; + +DROP TABLE t1, t2, t3, t4, t5, t6; --echo End of 5.0 tests diff --git a/sql/field.cc b/sql/field.cc index e6e4195ba1e..1a0e93c82ac 100644 --- a/sql/field.cc +++ b/sql/field.cc @@ -1304,7 +1304,8 @@ Field::Field(char *ptr_arg,uint32 length_arg,uchar *null_ptr_arg, field_name(field_name_arg), query_id(0), key_start(0), part_of_key(0), part_of_sortkey(0), unireg_check(unireg_check_arg), - field_length(length_arg), null_bit(null_bit_arg) + field_length(length_arg), null_bit(null_bit_arg), + is_created_from_null_item(FALSE) { flags=null_ptr ? 0: NOT_NULL_FLAG; comment.str= (char*) ""; diff --git a/sql/field.h b/sql/field.h index 4fcdb50f8c7..d9161d36dac 100644 --- a/sql/field.h +++ b/sql/field.h @@ -88,6 +88,16 @@ public: uint field_index; // field number in fields array uint16 flags; uchar null_bit; // Bit used to test null bit + /** + If true, this field was created in create_tmp_field_from_item from a NULL + value. This means that the type of the field is just a guess, and the type + may be freely coerced to another type. + + @see create_tmp_field_from_item + @see Item_type_holder::get_real_type + + */ + bool is_created_from_null_item; Field(char *ptr_arg,uint32 length_arg,uchar *null_ptr_arg,uchar null_bit_arg, utype unireg_check_arg, const char *field_name_arg, diff --git a/sql/item.cc b/sql/item.cc index 3177c0fb1e8..5df0f441619 100644 --- a/sql/item.cc +++ b/sql/item.cc @@ -6569,6 +6569,8 @@ enum_field_types Item_type_holder::get_real_type(Item *item) */ Field *field= ((Item_field *) item)->field; enum_field_types type= field->real_type(); + if (field->is_created_from_null_item) + return MYSQL_TYPE_NULL; /* work around about varchar type field detection */ if (type == MYSQL_TYPE_STRING && field->type() == MYSQL_TYPE_VAR_STRING) return MYSQL_TYPE_VAR_STRING; @@ -6820,6 +6822,8 @@ Field *Item_type_holder::make_field_by_type(TABLE *table) Field::NONE, name, table, get_set_pack_length(enum_set_typelib->count), enum_set_typelib, collation.collation); + case MYSQL_TYPE_NULL: + return make_string_field(table); default: break; } diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 3529de1c28a..74db7770c6f 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -8974,6 +8974,8 @@ static Field *create_tmp_field_from_item(THD *thd, Item *item, TABLE *table, *((*copy_func)++) = item; // Save for copy_funcs if (modify_item) item->set_result_field(new_field); + if (item->type() == MYSQL_TYPE_NULL) + new_field->is_created_from_null_item= TRUE; return new_field; } From a8d1b13f3e9f13efaf96039e51397b2fa67a982f Mon Sep 17 00:00:00 2001 From: unknown Date: Thu, 20 Dec 2007 10:58:21 +0100 Subject: [PATCH 2/2] Bug#32848: Data type conversion bug in union subselects in MySQL 5.0.38 Warnings elimination sql/sql_select.cc: Bug#32848: Warnings elimination --- sql/sql_select.cc | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 74db7770c6f..ed4b10e6221 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -8974,7 +8974,7 @@ static Field *create_tmp_field_from_item(THD *thd, Item *item, TABLE *table, *((*copy_func)++) = item; // Save for copy_funcs if (modify_item) item->set_result_field(new_field); - if (item->type() == MYSQL_TYPE_NULL) + if (item->type() == Item::NULL_ITEM) new_field->is_created_from_null_item= TRUE; return new_field; }