2 files changed, 50 insertions, 8 deletions
diff --git a/core/vm/sqlvm/ast/types.go b/core/vm/sqlvm/ast/types.go
index 65fdc501d..3909e7575 100644
--- a/core/vm/sqlvm/ast/types.go
+++ b/core/vm/sqlvm/ast/types.go
@@ -169,6 +169,17 @@ func DataTypeDecode(t DataType) (TypeNode, error) {
 	return nil, se.ErrorCodeDataTypeDecode
 }
 
+func decimalToBig(d decimal.Decimal) (b *big.Int) {
+	if exponent := int64(d.Exponent()); exponent >= 0 {
+		exp := new(big.Int).Exp(bigIntTen, big.NewInt(exponent), nil)
+		b = new(big.Int).Mul(d.Coefficient(), exp)
+	} else {
+		exp := new(big.Int).Exp(bigIntTen, big.NewInt(-exponent), nil)
+		b = new(big.Int).Div(d.Coefficient(), exp)
+	}
+	return
+}
+
 // Don't handle overflow here.
 func decimalEncode(size int, d decimal.Decimal) []byte {
 	ret := make([]byte, size)
@@ -177,14 +188,7 @@ func decimalEncode(size int, d decimal.Decimal) []byte {
 		return ret
 	}
 
-	var b *big.Int
-	if exponent := int64(d.Exponent()); exponent >= 0 {
-		exp := new(big.Int).Exp(bigIntTen, big.NewInt(exponent), nil)
-		b = new(big.Int).Mul(d.Coefficient(), exp)
-	} else {
-		exp := new(big.Int).Exp(bigIntTen, big.NewInt(-exponent), nil)
-		b = new(big.Int).Div(d.Coefficient(), exp)
-	}
+	b := decimalToBig(d)
 
 	if s > 0 {
 		bs := b.Bytes()
@@ -298,3 +302,16 @@ func GetMinMax(dt DataType) (min, max decimal.Decimal, err error) {
 	decPairMap[dt] = decPair{Max: max, Min: min}
 	return
 }
+
+// DecimalToUint64 convert decimal to uint64.
+// Negative case will return error, and decimal part will be trancated.
+func DecimalToUint64(d decimal.Decimal) (uint64, error) {
+	s := d.Sign()
+	if s == 0 {
+		return 0, nil
+	}
+	if s < 0 {
+		return 0, se.ErrorCodeNegDecimalToUint64
+	}
+	return decimalToBig(d).Uint64(), nil
+}
diff --git a/core/vm/sqlvm/ast/types_test.go b/core/vm/sqlvm/ast/types_test.go
index ada5d487f..8373aa344 100644
--- a/core/vm/sqlvm/ast/types_test.go
+++ b/core/vm/sqlvm/ast/types_test.go
@@ -212,6 +212,31 @@ func (s *TypesTestSuite) TestSize() {
 	}
 }
 
+func (s *TypesTestSuite) TestDecimalToUint64() {
+	pos := decimal.New(15, 1)
+	zero := decimal.Zero
+	neg := decimal.New(-150, -1)
+	posSmall := decimal.New(15, -2)
+	negSmall := decimal.New(-15, -2)
+
+	testcases := []struct {
+		d   decimal.Decimal
+		u   uint64
+		err error
+	}{
+		{pos, 150, nil},
+		{zero, 0, nil},
+		{neg, 0, errors.ErrorCodeNegDecimalToUint64},
+		{posSmall, 0, nil},
+		{negSmall, 0, errors.ErrorCodeNegDecimalToUint64},
+	}
+	for i, t := range testcases {
+		u, err := DecimalToUint64(t.d)
+		s.Require().Equalf(t.err, err, "err not match. testcase: %v", i)
+		s.Require().Equalf(t.u, u, "result not match. testcase: %v", i)
+	}
+}
+
 func TestTypes(t *testing.T) {
 	suite.Run(t, new(TypesTestSuite))
 }