@Override
    public String toString() {
        DdlResult ddlResult = this;
        StringBuilder sb = new StringBuilder();
        do {
            sb.append(String.format("DdlResult [schemaName=%s , tableName=%s , oriSchemaName=%s , oriTableName=%s , type=%s ];",
                ddlResult.schemaName,
                ddlResult.tableName,
                ddlResult.oriSchemaName,
                ddlResult.oriTableName,
                ddlResult.type));
            ddlResult = ddlResult.renameTableResult;
        } while (ddlResult != null);
        return sb.toString();
    }
@Test
  public void toStringOutputNotNull() {

    // Arrange
    final DdlResult objectUnderTest = new DdlResult();

    // Act
    final String actual = objectUnderTest.toString();

    // Assert result
    Assert.assertEquals(
        "DdlResult [schemaName=null , tableName=null , oriSchemaName=null , oriTableName=null , type=null ];",
        actual);
  }