# Turn a spreadsheet into a table

<TLDR>
Open **Add data**, choose **Turn a spreadsheet into a table**, upload the file, check the columns and select **Import**. Later files can add rows, update rows by key or replace all rows.
</TLDR>

## What you will build [#what-you-will-build]

A <Term id="table">table</Term> in <Term id="nexus">Nexus</Term>, your database, made from a spreadsheet or CSV file. You will describe its columns, add a check that keeps bad rows out, and load a second file. The original file is kept in a folder too.

## Before you start [#before-you-start]

- A spreadsheet (Excel) or CSV file with a header row.
- Access to add data. Owners and admins always have it; members need it given in [Data access](/docs/data/data-access).
- For developers: the <Term id="sdk">SDK</Term> installed and an <Term id="api-key">API key</Term>. See the [Quickstart](/docs/get-started/quickstart).

## Steps [#steps]

<ForEveryone>
<Steps>
<Step>
### Open Add data [#open-add-data]
Go to <AppLink to="data" /> and choose **Turn a spreadsheet into a table**.
</Step>
<Step>
### Upload the file [#upload-the-file]
Pick your file and the folder to keep it in. Klarety shows the **Columns found**.

<Screenshot src="/docs/_media/nexus-add-data.png" alt="The import dialog with the columns found" />
</Step>
<Step>
### Name the table and import [#name-the-table-and-import]
Check the **Table name**. If it already exists, choose **Add rows** or **Replace rows**. Select **Import**, then **Open table**.
</Step>
<Step>
### Describe the columns [#describe-the-columns]
Add a description to each column that is not obvious ("What this column holds"). The AI in Studios and agents reads them, so good ones give better answers.
</Step>
<Step>
### Add a data check [#add-a-data-check]
Open **Data checks** and select **Add check**, for example `order_id` is never empty, or `amount` is between 0 and 100000. Rows that fail are set aside when data is added.
</Step>
<Step>
### Load the next file [#load-the-next-file]
For a new version of the spreadsheet, open the table, choose **Add data from a file** and pick how it loads:

- **Add rows**: append the new rows.
- **Update rows by key**: match rows on a column such as `order_id`, update the ones that exist and add the rest.
- **Replace all rows**: the file becomes the whole table.
</Step>
</Steps>
</ForEveryone>

<ForDevelopers>
<Steps>
<Step>
### Load the file [#load-the-file]
```python
from klarety import Nexus

nx = Nexus.connect()
run = nx.ingest("orders.csv", into="orders", schema="default")
print(run.run_id, run.state)
```
</Step>
<Step>
### Preview before loading (optional) [#preview-before-loading-optional]
`ingest_preview` shows what Klarety found in the file without loading anything:

```python
print(nx.ingest_preview("orders.csv", into="orders"))
```
</Step>
<Step>
### Wait for it to finish [#wait-for-it-to-finish]
```python
status = nx.ingest_status(run.run_id)
print(status.state)
```
</Step>
<Step>
### Load the next file by key [#load-the-next-file-by-key]
```python
nx.ingest("orders_week2.csv", into="orders", mode="upsert", key=["order_id"])
```
`mode` is `auto`, `append`, `upsert` or `replace`. A file already loaded into a table is skipped unless you pass `force=True`.
</Step>
<Step>
### Or use the command line [#or-use-the-command-line]
```bash
klarety ingest orders.csv --into orders
klarety ingest orders_week2.csv --into orders --mode upsert --key order_id
```
</Step>
</Steps>
</ForDevelopers>

<Callout type="warn" title="Replace all rows overwrites the table">
The file becomes the whole table. If you choose it by mistake, use the table's **History** to go back.
</Callout>

## Check that it worked [#check-that-it-worked]

<ForEveryone>
Open the table from **Nexus Lakehouse**; the header shows its column and row counts. Select **Open in SQL editor** and run:

```sql
SELECT COUNT(*) FROM orders
```
</ForEveryone>

<ForDevelopers>
```python
print(nx.sql("SELECT COUNT(*) AS n FROM orders").rows)
```
</ForDevelopers>

The count matches the rows in your file, less any rows a check set aside. The table's **History** shows each load, with the rows it added.

## If something goes wrong [#if-something-goes-wrong]

<Accordions>
<Accordion title="The file is too large">
The upload dialog shows the size limit. Split the file, or load it from code or a connected source. See [Ingest data](/docs/developers/ingest).
</Accordion>
<Accordion title="Some rows are missing">
A data check set them aside. The table's check summary shows rows written and set aside in recent loads.
</Accordion>
<Accordion title="I loaded the wrong file">
Open the table's **History** and choose **Go back to this** on the version before the load. Every change after it is undone. See [Undo and restore](/docs/data/undo-and-restore).
</Accordion>
</Accordions>

## Next steps [#next-steps]

- [Ask your data a question](/docs/guides/first-query): query the table you just made.
- [Tables](/docs/data/tables): everything you can do with a table.
- [Add data](/docs/data/add-data): other ways to bring data in.
- [Send a daily report](/docs/guides/daily-report): summarise the table every morning.