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Backport of the patch for bug #8457 "Precision math: DIV

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returns incorrect result with large decimal value" 
 
For the DIV operator, neither operands nor result were checked 
for integer overflows. 
 
This patch changes the DIV behavior for non-integer operands as 
follows: if either of the operands has a non-integer type, 
convert both operands to the DECIMAL type, then calculate the 
division using DECIMAL arithmetics. Convert the resulting 
DECIMAL value into BIGINT [UNSIGNED] if it fits into the 
corresponding range, or throw an 'out of range' error 
otherwise. 

mysql-test/r/func_math.result:
  Added a test case for bug #8457.
  Fixed results for a test case depending on the wrong behavior.
mysql-test/r/type_varchar.result:
  Fixed results for a test case depending on the wrong behavior.
mysql-test/t/func_math.test:
  Added a test case for bug #8457.
sql/item_func.cc:
  If either of the operands has a non-integer type, convert both 
  operands to the DECIMAL type, then calculate the division using 
  DECIMAL arithmetics. Convert the resulting DECIMAL value into 
  BIGINT [UNSIGNED] if it fits into the corresponding range, or 
  throw an 'out of range' error otherwise.
This commit is contained in:
Alexey Kopytov
2009-10-13 12:31:42 +04:00
parent 4337c3808f
commit 7e3b4d21c0
4 changed files with 57 additions and 2 deletions
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11
mysql-test/r/func_math.result
View File

@ -382,6 +382,9 @@ y
SELECT b DIV 900 y FROM t1 GROUP BY y;
y
0
Warnings:
Warning 1366 Incorrect decimal value: '' for column '' at row -1
Warning 1366 Incorrect decimal value: '' for column '' at row -1
SELECT c DIV 900 y FROM t1 GROUP BY y;
y
0
@ -482,4 +485,12 @@ RAND(i)
0.155220427694936
DROP TABLE t1;
#
select 123456789012345678901234567890.123456789012345678901234567890 div 1 as x;
ERROR 22003: Out of range value for column 'x' at row 1
select "123456789012345678901234567890.123456789012345678901234567890" div 1 as x;
ERROR 22003: Out of range value for column 'x' at row 1
SHOW WARNINGS;
Level Code Message
Warning 1292 Truncated incorrect DECIMAL value: ''
Error 1264 Out of range value for column 'x' at row 1
End of 5.1 tests

5
mysql-test/r/type_varchar.result
View File

@ -475,8 +475,9 @@ a (a DIV 2)
60 30
t 0
Warnings:
Warning 1292 Truncated incorrect INTEGER value: '1a'
Warning 1292 Truncated incorrect INTEGER value: 't '
Warning 1292 Truncated incorrect DECIMAL value: '1a'
Warning 1366 Incorrect decimal value: '' for column '' at row -1
Warning 1292 Truncated incorrect DECIMAL value: 't '
SELECT a,CAST(a AS SIGNED) FROM t1 ORDER BY a;
a CAST(a AS SIGNED)
10 10

11
mysql-test/t/func_math.test
View File

@ -309,4 +309,15 @@ DROP TABLE t1;
--echo #
#
# Bug #8457: Precision math:
# DIV returns incorrect result with large decimal value
# Bug #46606:Casting error for large numbers in 5.4 when 'div' is used
--error ER_WARN_DATA_OUT_OF_RANGE
select 123456789012345678901234567890.123456789012345678901234567890 div 1 as x;
--error ER_WARN_DATA_OUT_OF_RANGE
select "123456789012345678901234567890.123456789012345678901234567890" div 1 as x;
SHOW WARNINGS;
--echo End of 5.1 tests

32
sql/item_func.cc
View File

@ -1348,6 +1348,38 @@ void Item_func_div::fix_length_and_dec()
longlong Item_func_int_div::val_int()
{
DBUG_ASSERT(fixed == 1);
/*
Perform division using DECIMAL math if either of the operands has a
non-integer type
*/
if (args[0]->result_type() != INT_RESULT ||
args[1]->result_type() != INT_RESULT)
{
my_decimal value0, value1, tmp;
my_decimal *val0, *val1;
longlong res;
int err;
val0= args[0]->val_decimal(&value0);
val1= args[1]->val_decimal(&value1);
if ((null_value= (args[0]->null_value || args[1]->null_value)))
return 0;
if ((err= my_decimal_div(E_DEC_FATAL_ERROR & ~E_DEC_DIV_ZERO, &tmp,
val0, val1, 0)) > 3)
{
if (err == E_DEC_DIV_ZERO)
signal_divide_by_null();
return 0;
}
if (my_decimal2int(E_DEC_FATAL_ERROR, &tmp, unsigned_flag, &res) &
E_DEC_OVERFLOW)
my_error(ER_WARN_DATA_OUT_OF_RANGE, MYF(0), name, 1);
return res;
}
longlong value=args[0]->val_int();
longlong val2=args[1]->val_int();
if ((null_value= (args[0]->null_value || args[1]->null_value)))