Support nil as query parameters

trino/etc/catalog/memory.properties

@@ -0,0 +1 @@
+connector.name=memory

trino/serial.go

@@ -99,7 +99,7 @@ func Timestamp(year int,
 func Serial(v interface{}) (string, error) {
 	switch x := v.(type) {
 	case nil:
-		return "", UnsupportedArgError{"<nil>"}
+		return "NULL", nil
 
 	// numbers convertible to int
 	case int8:

trino/serial_test.go

@@ -161,9 +161,9 @@ func TestSerial(t *testing.T) {
 			expectedSerial: "TIMESTAMP '2017-07-10 11:34:25.000123456 Z'",
 		},
 		{
-			name:          "nil",
-			value:         nil,
-			expectedError: true,
+			name:           "nil",
+			value:          nil,
+			expectedSerial: "NULL",
 		},
 		{
 			name:          "slice typed nil",

trino/trino.go

@@ -656,6 +656,8 @@ func (st *driverStmt) ExecContext(ctx context.Context, args []driver.NamedValue)
 
 func (st *driverStmt) CheckNamedValue(arg *driver.NamedValue) error {
 	switch arg.Value.(type) {
+	case nil:
+		return nil
 	case Numeric, trinoDate, trinoTime, trinoTimeTz, trinoTimestamp:
 		return nil
 	default:

trino/trino_test.go

@@ -1719,3 +1719,67 @@ func BenchmarkQuery(b *testing.B) {
 		rows.Close()
 	}
 }
+
+func TestExec(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping test in short mode.")
+	}
+	c := &Config{
+		ServerURI:         *integrationServerFlag,
+		SessionProperties: map[string]string{"query_priority": "1"},
+	}
+
+	dsn, err := c.FormatDSN()
+	require.NoError(t, err)
+
+	db, err := sql.Open("trino", dsn)
+	require.NoError(t, err)
+
+	t.Cleanup(func() {
+		assert.NoError(t, db.Close())
+	})
+
+	result, err := db.Exec("CREATE TABLE memory.default.test (id INTEGER, name VARCHAR, optional VARCHAR)")
+	require.NoError(t, err, "Failed executing CREATE TABLE query")
+
+	result, err = db.Exec("INSERT INTO memory.default.test (id, name, optional) VALUES (?, ?, ?), (?, ?, ?), (?, ?, ?)",
+		123, "abc", nil,
+		456, "def", "present",
+		789, "ghi", nil)
+	require.NoError(t, err, "Failed executing INSERT query")
+	_, err = result.LastInsertId()
+	assert.Error(t, err, "trino: operation not supported")
+	numRows, err := result.RowsAffected()
+	require.NoError(t, err, "Failed checking rows affected")
+	assert.Equal(t, numRows, int64(3))
+
+	rows, err := db.Query("SELECT * FROM memory.default.test")
+	require.NoError(t, err, "Failed executing DELETE query")
+
+	expectedIds := []int{123, 456, 789}
+	expectedNames := []string{"abc", "def", "ghi"}
+	expectedOptionals := []sql.NullString{
+		sql.NullString{Valid: false},
+		sql.NullString{String: "present", Valid: true},
+		sql.NullString{Valid: false},
+	}
+	actualIds := []int{}
+	actualNames := []string{}
+	actualOptionals := []sql.NullString{}
+	for rows.Next() {
+		var id int
+		var name string
+		var optional sql.NullString
+		require.NoError(t, rows.Scan(&id, &name, &optional), "Failed scanning query result")
+		actualIds = append(actualIds, id)
+		actualNames = append(actualNames, name)
+		actualOptionals = append(actualOptionals, optional)
+
+	}
+	assert.Equal(t, expectedIds, actualIds)
+	assert.Equal(t, expectedNames, actualNames)
+	assert.Equal(t, expectedOptionals, actualOptionals)
+
+	_, err = db.Exec("DROP TABLE memory.default.test")
+	require.NoError(t, err, "Failed executing DROP TABLE query")
+}