# Notebook variables

Define notebook-wide variables in the QuestDB Web Console and reference them as @name in every cell. Built on QuestDB's DECLARE syntax.

Variables let you define a value once (e.g. a symbol, a lookback window, a
threshold) and reference it as `@name` in every cell of the notebook. Change
it in one place and every query picks it up. Variables are built on QuestDB's
[DECLARE](/docs/query/sql/declare/) syntax.

## Defining variables

Click **Variables** on the notebook toolbar (it reads "Variables (N)" once
you have some). Each row is `@name := value`, where the value is any SQL
expression: a string, a number, an interval, or a function call.

[Screenshot: The variables popover with symbol and window variables defined](https://questdb.com/docs/images/docs/console/notebook-variables.webp)

**Add variable** appends a row. **Apply** validates every variable against
the server and shows errors inline on the failing row; **Cancel** (or
closing the popover) discards your draft.

A pair like this parameterizes a whole dashboard:

```questdb-sql title="Notebook variables as a DECLARE block"
DECLARE
  @symbol := 'BTC-USDT',
  @window := '$now - 1h..$now'
```

with cells querying `WHERE symbol = @symbol AND timestamp IN @window`.

## How variables are applied

Variables apply to every query in the notebook: cell runs, chart refreshes,
validation, and result downloads.

Order matters: a variable can reference variables defined above it. Drag the
handle at the left of a row to reorder. If a cell declares its own variables
with `DECLARE`, they are merged with the notebook's, and a cell-level variable
with the same name shadows the notebook one.

Charts pick up changed values on their next refresh; table results pick them
up when you re-run the cell.

## Copying and importing

The copy button copies your variables as a ready-to-paste `DECLARE` block, and
**Import from clipboard** parses a `DECLARE` block back into rows. This
round-trip moves variables between notebooks, or between a notebook and the
SQL editor.

## Next steps

- [Live dashboards](/docs/getting-started/web-console/notebooks/live-dashboards) uses variables to parameterize a whole board
- [Notebook charts](/docs/getting-started/web-console/notebooks/charts) covers drawing the queries variables feed into
- [DECLARE](/docs/query/sql/declare/) documents the underlying SQL syntax