Add events to Google Calendar listed in Google Spreadsheet.

add-events.gs

/**
 * | Start      | End        |   | Calendar  | Title | Done |
 * |------------|------------|---|-----------|-------|------|
 * | 3/26 13:00 | 3/26 14:00 |   |           | Lunch |      |
 * |------------|------------|---|-----------|-------|------|
 * | 3/26       |            | v | Birthdays | Alice |      |
 */
var INDEX = {
  START: 0,
  END: 1,
  WHOLE_DAY: 2,
  TITLE: 3,
  CAL: 4,
  DONE: 5,
}

function registerEvents() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheets()[0];
  
  // This represents ALL the data
  var range = sheet.getDataRange();
  var values = range.getValues();

  for (var i = 0; i < values.length; i++) {
    var row = values[i];
    // Find the calendar if the name is specified, otherwise use the default calnder.
    var cal = CalendarApp.getCalendarsByName(row[INDEX.CAL])[0] || CalendarApp.getDefaultCalendar();
    // Skip if the event is already registered.
    if (row[INDEX.DONE] != "") {
      continue;
    }
    
    var start = new Date(row[INDEX.START]);
    var title = row[INDEX.TITLE];
    if (row[INDEX.WHOLE_DAY] == "") {
      var end = new Date(row[INDEX.END]);
      cal.createEvent(title, start, end);
    } else {
      cal.createAllDayEvent(title, start);
    }
    
    // Mark as done.
    var done = range.getCell(i + 1, INDEX.DONE + 1);
    done.setValue("✓");
  }
}

How to run the script.

1. Create a new spreadsheet in Google Docs
2. Add a table of events in the following format:

Start	End	All Day	Calendar	Title	Done
3/26 13:00	3/26 14:00			Lunch
3/26		v	Birthdays	Alice

3. Click [Tool] > [Script Editor]
4. Copy-paste this script.
5. Run the registerEvents function