---
title: "TRUNCATE 语句"
weight: 8
type: docs
aliases:
- /zh/dev/table/sql/truncate.html
---
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<a name="truncate-statements"></a>

# TRUNCATE 语句

{{< label Batch >}}

TRUNCATE 语句用于删除表中的全部数据，但不会删除表本身。

<span class="label label-danger">注意</span> 目前, `TRUNCATE` 语句仅支持批模式, 并且要求目标表实现了 {{< gh_link file="flink-table/flink-table-common/src/main/java/org/apache/flink/table/connector/sink/abilities/SupportsTruncate.java" name="SupportsTruncate" >}} 接口。
如果在一个没有实现该接口的表上执行 `TRUNCATE` 语句，则会抛异常。

<a name="run-a-truncate-statement"></a>

## 执行 TRUNCATE 语句

{{< tabs "truncate" >}}
{{< tab "Java" >}}
可以使用 `TableEnvironment` 的 `executeSql()` 方法执行 TRUNCATE 语句。如果 TRUNCATE 操作执行失败，`executeSql()` 方法会抛出异常。

以下示例展示了如何在 `TableEnvironment` 中执行一条 TRUNCATE 语句。
{{< /tab >}}
{{< tab "Scala" >}}

可以使用 `TableEnvironment` 中的 `executeSql()` 方法执行 TRUNCATE 语句。如果 TRUNCATE 操作执行失败，`executeSql()` 方法会抛出异常。

以下的例子展示了如何在 `TableEnvironment` 中执行一条 TRUNCATE 语句。

{{< /tab >}}
{{< tab "Python" >}}

可以使用 `TableEnvironment` 中的 `execute_sql()` 方法执行 TRUNCATE 语句。如果 TRUNCATE 操作执行失败，`execute_sql()` 方法会抛出异常。

以下的例子展示了如何在 `TableEnvironment` 中执行一条 TRUNCATE 语句。

{{< /tab >}}
{{< tab "SQL CLI" >}}

TRUNCATE 语句可以在 [SQL CLI]({{< ref "docs/dev/table/sqlClient" >}}) 中执行。

以下示例展示了如何在 SQL CLI 中执行一条 TRUNCATE 语句。

{{< /tab >}}
{{< /tabs >}}

{{< tabs "a5de1760-e363-4b8d-9d6f-0bacb35b9dcf" >}}
{{< tab "Java" >}}
```java
EnvironmentSettings settings = EnvironmentSettings.newInstance().inBatchMode().build();
TableEnvironment tEnv = TableEnvironment.create(settings);

// 注册 "Orders" 表
tEnv.executeSql("CREATE TABLE Orders (`user` STRING, product STRING, amount INT) WITH (...)");

// 插入数据
tEnv.executeSql("INSERT INTO Orders VALUES ('Lili', 'Apple', 1), ('Jessica', 'Banana', 2), ('Mr.White', 'Chicken', 3)").await();
tEnv.executeSql("SELECT * FROM Orders").print();
// +--------------------------------+--------------------------------+-------------+
// |                           user |                        product |      amount |
// +--------------------------------+--------------------------------+-------------+
// |                           Lili |                          Apple |           1 |
// |                        Jessica |                         Banana |           2 |
// |                       Mr.White |                        Chicken |           3 |
// +--------------------------------+--------------------------------+-------------+
// 3 rows in set
        
// 清理 "Orders" 表数据
tEnv.executeSql("TRUNCATE TABLE Orders").await();
tEnv.executeSql("SELECT * FROM Orders").print();
// 返回空结果
```
{{< /tab >}}
{{< tab "Scala" >}}
```scala
val env = StreamExecutionEnvironment.getExecutionEnvironment()
val settings = EnvironmentSettings.newInstance().inBatchMode().build()
val tEnv = StreamTableEnvironment.create(env, settings)

// 注册一个 "Orders" 表
tEnv.executeSql("CREATE TABLE Orders (`user` STRING, product STRING, amount INT) WITH (...)")
// 插入原始数据
tEnv.executeSql("INSERT INTO Orders VALUES ('Lili', 'Apple', 1), ('Jessica', 'Banana', 2), ('Mr.White', 'Chicken', 3)").await()
tEnv.executeSql("SELECT * FROM Orders").print()
// +--------------------------------+--------------------------------+-------------+
// |                           user |                        product |      amount |
// +--------------------------------+--------------------------------+-------------+
// |                           Lili |                          Apple |           1 |
// |                        Jessica |                         Banana |           2 |
// |                       Mr.White |                        Chicken |           3 |
// +--------------------------------+--------------------------------+-------------+
// 3 rows in set
// 全表删除数据
tEnv.executeSql("TRUNCATE TABLE Orders").await()
tEnv.executeSql("SELECT * FROM Orders").print()
// Empty set
```
{{< /tab >}}
{{< tab "Python" >}}
```python
env_settings = EnvironmentSettings.in_batch_mode()
table_env = TableEnvironment.create(env_settings)

# 注册一个 "Orders" 表
table_env.execute_sql("CREATE TABLE Orders (`user` STRING, product STRING, amount INT) WITH (...)")
# 插入原始数据
table_env.execute_sql("INSERT INTO Orders VALUES ('Lili', 'Apple', 1), ('Jessica', 'Banana', 2), ('Mr.White', 'Chicken', 3)").wait()
table_env.execute_sql("SELECT * FROM Orders").print()
# +--------------------------------+--------------------------------+-------------+
# |                           user |                        product |      amount |
# +--------------------------------+--------------------------------+-------------+
# |                           Lili |                          Apple |           1 |
# |                        Jessica |                         Banana |           2 |
# |                       Mr.White |                        Chicken |           3 |
# +--------------------------------+--------------------------------+-------------+
# 3 rows in set
# 全表删除数据
table_env.execute_sql("TRUNCATE TABLE Orders").wait()
table_env.execute_sql("SELECT * FROM Orders").print()
# Empty set
```
{{< /tab >}}
{{< tab "SQL CLI" >}}
```sql
Flink SQL> SET 'execution.runtime-mode' = 'batch';
[INFO] Session property has been set.

Flink SQL> CREATE TABLE Orders (`user` STRING, product STRING, amount INT) with (...);
[INFO] Execute statement succeeded.

Flink SQL> INSERT INTO Orders VALUES ('Lili', 'Apple', 1), ('Jessica', 'Banana', 1), ('Mr.White', 'Chicken', 3);
[INFO] Submitting SQL update statement to the cluster...
[INFO] SQL update statement has been successfully submitted to the cluster:
Job ID: bd2c46a7b2769d5c559abd73ecde82e9

Flink SQL> SELECT * FROM Orders;
    user                         product      amount
    Lili                           Apple           1
 Jessica                          Banana           2
Mr.White                         Chicken           3

Flink SQL> TRUNCATE TABLE Orders;
[INFO] Execute statement succeeded.

Flink SQL> SELECT * FROM Orders;
// Empty set
```
{{< /tab >}}
{{< /tabs >}}

{{< top >}}

<a name="syntax"></a>

## 语法

```sql
TRUNCATE TABLE [catalog_name.][db_name.]table_name
```
