# append-datatables

## Description

<mark style="color:purple;">`append-datatables`</mark> *adaptor combines rows from two datatables into one datatable.*

The output datatable includes all rows from the `first` datatable followed by all rows from `second` datatable. The number of rows in the output datatable will be exactly the sum of the rows in `first` datatable and `second` datatable.

By default, the output datatable will include all columns from both datatables, this can be changed by setting `exclude unmatched columns` to true to exclude columns which do not exist in both datatables.

This adaptor is similar to a [SQL UNION Operator](https://www.w3schools.com/sql/sql_union.asp), please consider using the [<mark style="color:purple;">`join-datatables`</mark> ](https://cgps.gitbook.io/data-flo/reference-guide/join-datatables)adaptor to perform a [SQL JOIN](https://www.w3schools.com/sql/sql_join.asp) operation.

## Inputs

**`first data`**\
Type: `datatable`\
Required: Yes\
The first datatable.

**`second data`**\
Type: `datatable`\
Required: Yes\
The second datatable.

**`exclude unmatched columns`**\
Type: `boolean`\
Required: No\
Specifies whether to exclude columns which do not exist in both datatables. If unspecified, defaults to `False` (all columns from both datatables will be included).

## Outputs

**`data`**\
Type: `datatable`\
A datatable containing rows from both datatables.

## Examples

### Example 1: Default behaviour.

#### Inputs:

`first data`:

<table><thead><tr><th width="119.33333333333334">Month</th><th width="129">Sales (USD)</th><th width="129">Sales (GBP)</th></tr></thead><tbody><tr><td>Jan</td><td>1458</td><td>1156</td></tr><tr><td>Feb</td><td>9874</td><td>7835</td></tr></tbody></table>

`second data`:

<table><thead><tr><th width="142.33333333333334">Month</th><th width="128">Sales (USD)</th><th width="132">Sales (EUR)</th></tr></thead><tbody><tr><td>Mar</td><td>4562</td><td>4173</td></tr><tr><td>Apr</td><td>3654</td><td>3342</td></tr></tbody></table>

`exclude unmatched columns:` *null(empty)*

#### Outputs:

`data`:

<table><thead><tr><th width="239">Month</th><th width="129">Sales (USD)</th><th width="122">Sales (GBP)</th><th width="127">Sales (EUR)</th></tr></thead><tbody><tr><td>Jan</td><td>1458</td><td>1156</td><td></td></tr><tr><td>Feb</td><td>9874</td><td>7835</td><td></td></tr><tr><td>Mar</td><td>4562</td><td></td><td>4173</td></tr><tr><td>Apr</td><td>3654</td><td></td><td>3342</td></tr></tbody></table>

-> Appended two datatables and included the unmatched columns.

### Example 2: Excluding unmatched columns.

#### Inputs:

`first data`:

<table><thead><tr><th width="107.33333333333334">Month</th><th width="129">Sales (USD)</th><th width="129">Sales (GBP)</th></tr></thead><tbody><tr><td>Jan</td><td>1458</td><td>1156</td></tr><tr><td>Feb</td><td>9874</td><td>7835</td></tr></tbody></table>

`second data`:

<table><thead><tr><th width="125.33333333333334">Month</th><th width="128">Sales (USD)</th><th width="132">Sales (EUR)</th></tr></thead><tbody><tr><td>Mar</td><td>4562</td><td>4173</td></tr><tr><td>Apr</td><td>3654</td><td>3342</td></tr></tbody></table>

`exclude unmatched columns`: True

#### Outputs:

`data`:

<table><thead><tr><th width="165">Month</th><th width="127">Sales (USD)</th></tr></thead><tbody><tr><td>Jan</td><td>1458</td></tr><tr><td>Feb</td><td>9874</td></tr><tr><td>Mar</td><td>4562</td></tr><tr><td>Apr</td><td>3654</td></tr></tbody></table>

-> Appended two datatables and excluded the unmatched columns.

## Use cases

* Users are able to combine results from multiple sources.
* Users can add additional observations or records to an existing datatable.
* Users can combine time-series data from different time periods.