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88 lines
3.2 KiB
Markdown
88 lines
3.2 KiB
Markdown
---
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slug: /en/sql-reference/window-functions/lagInFrame
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sidebar_label: lagInFrame
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sidebar_position: 9
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---
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# lagInFrame
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Returns a value evaluated at the row that is at a specified physical offset row before the current row within the ordered frame.
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:::warning
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`lagInFrame` behavior differs from the standard SQL `lag` window function.
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Clickhouse window function `lagInFrame` respects the window frame.
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To get behavior identical to the `lag`, use `ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING`.
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:::
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**Syntax**
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```sql
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lagInFrame(x[, offset[, default]])
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OVER ([[PARTITION BY grouping_column] [ORDER BY sorting_column]
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[ROWS or RANGE expression_to_bound_rows_withing_the_group]] | [window_name])
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FROM table_name
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WINDOW window_name as ([[PARTITION BY grouping_column] [ORDER BY sorting_column])
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```
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For more detail on window function syntax see: [Window Functions - Syntax](./index.md/#syntax).
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**Parameters**
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- `x` — Column name.
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- `offset` — Offset to apply. [(U)Int*](../data-types/int-uint.md). (Optional - `1` by default).
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- `default` — Value to return if calculated row exceeds the boundaries of the window frame. (Optional - default value of column type when omitted).
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**Returned value**
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- Value evaluated at the row that is at a specified physical offset before the current row within the ordered frame.
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**Example**
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This example looks at historical data for a specific stock and uses the `lagInFrame` function to calculate a day-to-day delta and percentage change in the closing price of the stock.
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Query:
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```sql
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CREATE TABLE stock_prices
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(
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`date` Date,
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`open` Float32, -- opening price
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`high` Float32, -- daily high
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`low` Float32, -- daily low
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`close` Float32, -- closing price
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`volume` UInt32 -- trade volume
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)
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Engine = Memory;
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INSERT INTO stock_prices FORMAT Values
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('2024-06-03', 113.62, 115.00, 112.00, 115.00, 438392000),
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('2024-06-04', 115.72, 116.60, 114.04, 116.44, 403324000),
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('2024-06-05', 118.37, 122.45, 117.47, 122.44, 528402000),
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('2024-06-06', 124.05, 125.59, 118.32, 121.00, 664696000),
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('2024-06-07', 119.77, 121.69, 118.02, 120.89, 412386000);
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```
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```sql
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SELECT
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date,
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close,
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lagInFrame(close, 1, close) OVER (ORDER BY date ASC
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ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
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) AS previous_day_close,
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COALESCE(ROUND(close - previous_day_close, 2)) AS delta,
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COALESCE(ROUND((delta / previous_day_close) * 100, 2)) AS percent_change
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FROM stock_prices
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ORDER BY date DESC
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```
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Result:
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```response
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┌───────date─┬──close─┬─previous_day_close─┬─delta─┬─percent_change─┐
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1. │ 2024-06-07 │ 120.89 │ 121 │ -0.11 │ -0.09 │
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2. │ 2024-06-06 │ 121 │ 122.44 │ -1.44 │ -1.18 │
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3. │ 2024-06-05 │ 122.44 │ 116.44 │ 6 │ 5.15 │
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4. │ 2024-06-04 │ 116.44 │ 115 │ 1.44 │ 1.25 │
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5. │ 2024-06-03 │ 115 │ 115 │ 0 │ 0 │
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└────────────┴────────┴────────────────────┴───────┴────────────────┘
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```
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