TRUNCATE 语句
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TRUNCATE 语句 #

Batch

TRUNCATE 语句用于删除表中的全部数据，但不会删除表本身。

注意 目前, TRUNCATE 语句仅支持批模式, 并且要求目标表实现了 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。

执行 TRUNCATE 语句 #

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。

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。

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。

TRUNCATE 语句可以在 SQL CLI 中执行。

以下示例展示了如何在 SQL CLI 中执行一条 TRUNCATE 语句。

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

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

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

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

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语法 # 

TRUNCATE TABLE [catalog_name.][db_name.]table_name