diff options
Diffstat (limited to 'sql/item_func.cc')
-rw-r--r-- | sql/item_func.cc | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/sql/item_func.cc b/sql/item_func.cc index 0eab370237d..4138573785e 100644 --- a/sql/item_func.cc +++ b/sql/item_func.cc @@ -4056,6 +4056,105 @@ void Item_func_set_user_var::make_field(Send_field *tmp_field) Item::make_field(tmp_field); } + +/* + Save the value of a user variable into a field + + SYNOPSIS + save_in_field() + field target field to save the value to + no_conversion flag indicating whether conversions are allowed + + DESCRIPTION + Save the function value into a field and update the user variable + accordingly. If a result field is defined and the target field doesn't + coincide with it then the value from the result field will be used as + the new value of the user variable. + + The reason to have this method rather than simply using the result + field in the val_xxx() methods is that the value from the result field + not always can be used when the result field is defined. + Let's consider the following cases: + 1) when filling a tmp table the result field is defined but the value of it + is undefined because it has to be produced yet. Thus we can't use it. + 2) on execution of an INSERT ... SELECT statement the save_in_field() + function will be called to fill the data in the new record. If the SELECT + part uses a tmp table then the result field is defined and should be + used in order to get the correct result. + + The difference between the SET_USER_VAR function and regular functions + like CONCAT is that the Item_func objects for the regular functions are + replaced by Item_field objects after the values of these functions have + been stored in a tmp table. Yet an object of the Item_field class cannot + be used to update a user variable. + Due to this we have to handle the result field in a special way here and + in the Item_func_set_user_var::send() function. + + RETURN VALUES + FALSE Ok + TRUE Error +*/ + +int Item_func_set_user_var::save_in_field(Field *field, bool no_conversions) +{ + bool use_result_field= (result_field && result_field != field); + int error; + + /* Update the value of the user variable */ + check(use_result_field); + update(); + + if (result_type() == STRING_RESULT || + result_type() == REAL_RESULT && + field->result_type() == STRING_RESULT) + { + String *result; + CHARSET_INFO *cs= collation.collation; + char buff[MAX_FIELD_WIDTH]; // Alloc buffer for small columns + str_value.set_quick(buff, sizeof(buff), cs); + result= entry->val_str(&null_value, &str_value, decimals); + + if (null_value) + { + str_value.set_quick(0, 0, cs); + return set_field_to_null_with_conversions(field, no_conversions); + } + + /* NOTE: If null_value == FALSE, "result" must be not NULL. */ + + field->set_notnull(); + error=field->store(result->ptr(),result->length(),cs); + str_value.set_quick(0, 0, cs); + } + else if (result_type() == REAL_RESULT) + { + double nr= entry->val_real(&null_value); + if (null_value) + return set_field_to_null(field); + field->set_notnull(); + error=field->store(nr); + } + else if (result_type() == DECIMAL_RESULT) + { + my_decimal decimal_value; + my_decimal *value= entry->val_decimal(&null_value, &decimal_value); + if (null_value) + return set_field_to_null(field); + field->set_notnull(); + error=field->store_decimal(value); + } + else + { + longlong nr= entry->val_int(&null_value); + if (null_value) + return set_field_to_null_with_conversions(field, no_conversions); + field->set_notnull(); + error=field->store(nr, unsigned_flag); + } + return error; +} + + String * Item_func_get_user_var::val_str(String *str) { |