fix / and div operations on value of decimal type column
#1622
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fulghum
approved these changes
Feb 28, 2023
sql/expression/div.go
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| @@ -717,9 +742,11 @@ func intDiv(ctx *sql.Context, lval, rval interface{}) (interface{}, error) { | |||
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| // intDiv operation gets the integer part of the divided value | |||
| divRes := l.DivRound(r, 2) | |||
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Could we pass in 0 here as the precision and avoid the call to divRes.Truncate(0) on line 748? Seems like that might be a little more direct, since we don't ever need those decimal digits.
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Ah DivRound rounds the result value with defined precision, but int division only takes int part without rounding the result, which is why I have it do this weird steps 😅
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I just made it more clear and added comment for this behavior.
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| // this operation is only done on the left value as the scale/fraction part of the leftmost value | ||
| // is used to calculate the scale of the final result. If the value is GetField of decimal type column | ||
| // the decimal value evaluated does not always match the scale of column type definition |
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The cases fixed are:
DECIMAL(25,10)and the value stored is4990. This value is evaluated with 0 scale, whereas this should be evaluated as value with scale of 10.IntPart()function of decimal package returns 0 as undefined value for out of range values. This causes it hard to differentiate between cases where the final result is valid value of 0 and the final result is out of range value.