ignore, not coalesce

src/database/sql/convert.go

@@ -212,9 +212,8 @@ func convertAssign(dest, src any) error {
 	return convertAssignRows(dest, src, nil)
 }
 
-// coalesceNullValuesToZero determines whether to interpret null values from SQL as the
-// equivalent zero value in go
-var coalesceNullValuesToZero = false
+// ignoreNullValues determines whether to ignore null values in SQL
+var ignoreNullValues = false
 
 // convertAssignRows copies to dest the value in src, converting it if possible.
 // An error is returned if the copy would result in loss of information.
@@ -319,15 +318,8 @@ func convertAssignRows(dest, src any, rows *Rows) error {
 			*d = nil
 			return nil
 		default:
-			if coalesceNullValuesToZero {
-				dpv := reflect.ValueOf(d)
-				if dpv.Kind() == reflect.Pointer {
-					dv := reflect.Indirect(dpv)
-					dv.Set(reflect.Zero(dv.Type()))
-					return nil
-				} else {
-					return errors.New("destination not a pointer")
-				}
+			if ignoreNullValues {
+				return nil
 			}
 		}
 	// The driver is returning a cursor the client may iterate over.

src/database/sql/sql_test.go

@@ -1496,7 +1496,6 @@ func TestCursorFake(t *testing.T) {
 }
 
 func TestInvalidNilValues(t *testing.T) {
-	coalesceNullValuesToZero = false
 
 	var date1 time.Time
 	var date2 int
@@ -1549,7 +1548,8 @@ func TestInvalidNilValues(t *testing.T) {
 }
 
 func TestValidNilValues(t *testing.T) {
-	coalesceNullValuesToZero = true
+	ignoreNullValues = true
+	defer func() { ignoreNullValues = false }()
 
 	var date1 time.Time
 	var int1 int
@@ -1616,12 +1616,12 @@ func TestValidNilValues(t *testing.T) {
 			conn.dc.ci.(*fakeConn).skipDirtySession = true
 			defer conn.Close()
 
-			zeroVal := reflect.Zero(reflect.Indirect(reflect.ValueOf(tt.input)).Type())
+			originalValue := tt.input
 			err = conn.QueryRowContext(ctx, "SELECT|people|bdate|age=?", 1).Scan(tt.input)
 			if err != nil {
 				t.Fatalf("expected no error when querying nil column, but get %s", err.Error())
-			} else if !reflect.Indirect(reflect.ValueOf(tt.input)).Equal(zeroVal) {
-				t.Fatalf("expected scan to coalesce to zero value %v, but got %v", zeroVal, reflect.Indirect(reflect.ValueOf(tt.input)))
+			} else if tt.input != originalValue {
+				t.Fatalf("expected null scan to preserve original value %v, but got %v", originalValue, tt.input)
 			}
 
 			err = conn.PingContext(ctx)