Restrict conversion to whole numbers

pkg/connection/result_set.go

@@ -5,6 +5,7 @@ import (
 	"database/sql"
 	"database/sql/driver"
 	"io"
+	"math"
 	"reflect"
 	"sync"
 
@@ -111,7 +112,7 @@ func (results *QueryResults) getColumnValue(columnIndex int) driver.Value {
 // See https://github.com/exasol/exasol-driver-go/issues/113 for details.
 func convertValue(value any, columnType types.SqlQueryColumnType) driver.Value {
 	if isIntegerColumn(columnType) {
-		if floatValue, ok := value.(float64); ok {
+		if floatValue, ok := value.(float64); ok && isIntegerValue(floatValue) {
 			return int64(floatValue)
 		}
 	}
@@ -122,6 +123,10 @@ func isIntegerColumn(columnType types.SqlQueryColumnType) bool {
 	return columnType.Type == "DECIMAL" && columnType.Scale != nil && *columnType.Scale == 0
 }
 
+func isIntegerValue(value float64) bool {
+	return value == math.Trunc(value)
+}
+
 func (results *QueryResults) fetchNextRowChunk() error {
 	chunk := &types.SqlQueryResponseResultSetData{}
 	err := results.con.Send(context.Background(), &types.FetchCommand{

pkg/connection/result_set_test.go

@@ -290,8 +290,10 @@ func (suite *ResultSetTestSuite) TestConvertValue() {
 		columnType    types.SqlQueryColumnType
 		expectedValue driver.Value
 	}{
-		{float64(1.1), decimalTypeZeroScale, int64(1)}, // Only this combination will convert the value
-		{1.1, decimalTypeZeroScale, int64(1)},
+		{float64(1), decimalTypeZeroScale, int64(1)},                     // Only this combination will convert the value
+		{float64(-1), decimalTypeZeroScale, int64(-1)},                   // Only this combination will convert the value
+		{float64(10000000000), decimalTypeZeroScale, int64(10000000000)}, // Only this combination will convert the value
+		{1.1, decimalTypeZeroScale, float64(1.1)},
 		{float32(1.1), decimalTypeZeroScale, float32(1.1)},
 		{"string", decimalTypeZeroScale, "string"},
 		{true, decimalTypeZeroScale, true},