date-format.Rmd

---
title: "Date and Period Format"
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```
This guide explains how to specify dates and periods when working with the `khisr` package, which interacts with the DHIS2 platform. Understanding these formats is essential for retrieving the desired data effectively.

DHIS2 uses the `yyyy-MM-dd` format for dates. For instance, to represent March 20, 2024, you would use "2024-03-20".

### Specifying Periods

DHIS2 allows you to define periods in two ways:
- **Fixed Periods:** Refer to specific calendar periods (e.g., January 2024, 2020 to 2024).
- **Relative Periods:** Defined in relation to the current date (e.g., last year, last month, this quarter).



## Fixed Periods

The period format is described in the following table (also available on [get_period_types()]):

| Interval             | Format       | Example     | Description                            |
|:---------------------|:-------------|:------------|:---------------------------------------|
| Day                  | yyyyMMdd     | 20040315    | March 15, 2004                         |
| Week                 | yyyyWn       | 2004W10     | Week 10, 2004                          |
| Week Wednesday       | yyyyWedWn    | 2015WedW5   | Week 5 with start on Wednesday         |
| Week Thursday        | yyyyThuWn    | 2015ThuW6   | Week 6 with start on Thursday          |
| Week Saturday        | yyyySatWn    | 2015SatW7   | Week 7 with start on Saturday          |
| Week Sunday          | yyyySunWn    | 2015SunW8   | Week 8 with start on Sunday            |
| Bi-week              | yyyyBiWn     | 2015BiW1    | Weeks 1-2, 2015                        |
| Month                | yyyyMM       | 200403      | March 2004                             |
| Bi-month             | yyyyMMB      | 200401B     | January-February 2004                  |
| Quarter              | yyyyQn       | 2004Q1      | January-March 2004                     |
| Six-month            | yyyySn       | 2004S1      | January-June 2004                      |
| Six-month April      | yyyyAprilSn  | 2004AprilS1 | April-September 2004                   |
| Year                 | yyyy         | 2004        | 2004                                   |
| Financial Year April | yyyyApril    | 2004April   | April 2004 - March 2005                |
| Financial Year July  | yyyyJuly     | 2004July    | July 2004 - June 2005                  |
| Financial Year Oct   | yyyyOct      | 2004Oct     | October 2004 - September 2005          |

## Relative Periods

You can also utilize relative periods in addition to fixed periods (defined above). The available relative period values are:

- THIS_WEEK, LAST_WEEK, LAST_4_WEEKS, LAST_12_WEEKS, LAST_52_WEEKS,
- THIS_MONTH, LAST_MONTH, THIS_BIMONTH, LAST_BIMONTH, THIS_QUARTER, LAST_QUARTER,
- THIS_SIX_MONTH, LAST_SIX_MONTH, MONTHS_THIS_YEAR, QUARTERS_THIS_YEAR,
- THIS_YEAR, MONTHS_LAST_YEAR, QUARTERS_LAST_YEAR, LAST_YEAR, LAST_5_YEARS, LAST_10_YEARS, LAST_10_FINANCIAL_YEARS, LAST_12_MONTHS,
- LAST_3_MONTHS, LAST_6_BIMONTHS, LAST_4_QUARTERS, LAST_2_SIXMONTHS, THIS_FINANCIAL_YEAR,
- LAST_FINANCIAL_YEAR, LAST_5_FINANCIAL_YEARS