> ## Documentation Index
> Fetch the complete documentation index at: https://docs.risingwave.com/llms.txt
> Use this file to discover all available pages before exploring further.

# UPDATE

> Use the `UPDATE` command to modify values of existing rows in a table.

<Note>
  * `UPDATE` cannot modify data in the primary key column of a table.
  * Call [FLUSH](/sql/commands/sql-flush) after `UPDATE` to persist the changes to storage. This ensures that the changes are committed and visible for subsequent reads.
  * If you only need the `UPDATE` to wait until it is included in a successful checkpoint, you can enable [`DML_WAIT_PERSISTENCE`](/sql/commands/sql-set-dml-wait-persistence). This does not provide the same immediate read-after-write visibility as `FLUSH`.
</Note>

## Syntax

```sql theme={null}
UPDATE table_name
    SET { col_name = value, ... | ( col_name, ... ) = ( value, ... ) }
    [ WHERE condition ]
    [ RETURNING col_name ];
```

## Parameters

| Parameter or clause           | Description                                                                                                                                                                                                                                                                      |
| :---------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| *table\_name*                 | The table whose rows you want to update.                                                                                                                                                                                                                                         |
| **SET** *col\_name* = *value* | Assign a value or result of an expression to a specific column.*col\_name* cannot be a primary key.                                                                                                                                                                              |
| **WHERE** *condition*         | Specify which rows you want to update using an expression that returns a boolean value. Rows for which this expression returns true will be updated.  If you omit the WHERE clause, all rows in the table will be updated. Subqueries are supported in the condition expression. |
| **RETURNING**                 | Returns the values of any column based on each updated row.                                                                                                                                                                                                                      |

## Example

The `taxi_trips` table has three records:

```sql theme={null}
SELECT * FROM taxi_trips;
```

```sql theme={null}
 id | distance |    city
----+----------+-------------
  1 |       16 | Yerba Buena
  2 |       23 | New York
  3 |        6 | Chicago
(3 rows)
```

The following statement updates the city name from 'Yerba Buena' to 'San Francisco'. Also, it returns the value of *id* for the updated rows.

```sql theme={null}
UPDATE taxi_trips
SET city = 'San Francisco'
WHERE city = 'Yerba Buena'
RETURNING id;
```

The following statement converts the distance unit from kilometer to mile for certain areas.

```sql theme={null}
UPDATE taxi_trips
SET distance = distance * 0.6214
WHERE city NOT IN (SELECT city FROM restricted_zones);
```