Bugfix/int64 (#6)

* handle int64

* int64 fix v2

* remove driver

* int64 comment

gonull.go

@@ -6,6 +6,7 @@ import (
 	"database/sql/driver"
 	"encoding/json"
 	"errors"
+	"reflect"
 )
 
 var (
@@ -52,7 +53,7 @@ func (n Nullable[T]) Value() (driver.Value, error) {
 	if !n.Valid {
 		return nil, nil
 	}
-	return driver.Value(n.Val), nil
+	return n.Val, nil
 }
 
 // UnmarshalJSON implements the json.Unmarshaler interface for Nullable, allowing it to be used as a nullable field in JSON operations.
@@ -96,8 +97,18 @@ func convertToType[T any](value interface{}) (T, error) {
 	switch v := value.(type) {
 	case T:
 		return v, nil
-	default:
-		var zero T
-		return zero, ErrUnsupportedConversion
+	case int64:
+		// This case handles the situation when the input value is of type int64.
+		// It attempts to convert the int64 value to the target numeric type T if possible.
+		// If the conversion is successful, it returns the converted value of type T and a nil error.
+		// If the conversion is not possible, the function will continue to the next case (return an error).
+		switch t := reflect.Zero(reflect.TypeOf((*T)(nil)).Elem()).Interface().(type) {
+		case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64:
+			if reflect.TypeOf(t).ConvertibleTo(reflect.TypeOf((*T)(nil)).Elem()) {
+				return reflect.ValueOf(value).Convert(reflect.TypeOf((*T)(nil)).Elem()).Interface().(T), nil
+			}
+		}
 	}
+	var zero T
+	return zero, ErrUnsupportedConversion
 }