# BEGIN

The `BEGIN` command commits any existing open transaction on the current connection and starts a new transaction.

## Syntax

```
START TRANSACTION | BEGIN [WORK]

```

## Remarks

* This command must be run on the master aggregator or a child aggregator node (see [Node Requirements for SingleStore Commands](https://docs.singlestore.com/db/v9.1/reference/sql-reference/cluster-management-commands.md). Note that you must connect to the master aggregator when running this command on reference tables.
* When `BEGIN` is used to start a transaction, it overrides the behavior of `autocommit` engine variable for this transaction, and the transaction must be ended explicitly with `COMMIT` or `ROLLBACK`.
* If the transaction is successful, execute the [COMMIT](https://docs.singlestore.com/db/v9.1/reference/sql-reference/data-manipulation-language-dml/commit.md) command to commit the changes; if the transaction is unsuccessful or needs to be reverted, then execute the [ROLLBACK](https://docs.singlestore.com/db/v9.1/reference/sql-reference/data-manipulation-language-dml/rollback.md) command to revert the changes.
* The maximum number of tables that can be written into a single transaction is 1024. If the transaction table writes exceed the maximum amount, an error will be generated. Execute the `ROLLBACK` command to revert any changes. Then split the transaction into smaller sections and execute again.

## Example

For this example, consider the following `Employee` table:

| ID | Name |
| -- | ---- |
| 30 | Jim  |
| 20 | Rob  |
| 40 | Rick |

```sql
BEGIN;

```

```sql
UPDATE Employee SET Name = "John" WHERE ID = 300;

```

```output

Query OK, 0 rows affected (0.00 sec)
Rows matched: 0  Changed: 0  Warnings: 0

```

Run the `SELECT` query to verify if the `UPDATE` is correct:

```sql
SELECT * FROM Employee;

```

```output

+------+-------+
| ID   | Name  |
+------+-------+
|   30 | Jim   |
|   20 | Rob   |
|   40 | Rick  |
+------+-------+

```

Run `ROLLBACK` since there were no matching results for the `ID` and the `UPDATE` was not successful.

```sql
ROLLBACK;

```

**Note**: Before the user runs `COMMIT` or `ROLLBACK`, only that user can see the updates made after `BEGIN` was run.

***

Modified at: June 11, 2026

Source: [/db/v9.1/reference/sql-reference/data-manipulation-language-dml/begin/](https://docs.singlestore.com/db/v9.1/reference/sql-reference/data-manipulation-language-dml/begin/)

(An index of the documentation is available at /llms.txt)