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adjust data insert content in table (#1103)
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‎src/UserGuide/Master/Table/Basic-Concept/Write-Updata-Data_apache.md‎

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# Write & Update Data
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## 1. Data Insertion
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## 1. SQL Insertion
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### 1.1 Syntax
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<img src="/img/%E6%95%B0%E6%8D%AE%E5%86%99%E5%85%A5%E8%8B%B1%E6%96%87.png" alt="" style="width: 70%;"/>
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</div>
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### 1.2 Automatically Create Tables via Session Insertion
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When performing data writing through Session, IoTDB supports schema-less writing: there is no need to manually create tables beforehand. The system automatically constructs the table structure based on the information in the write request, and then directly executes the data writing operation.
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**Example:**
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```Java
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try (ITableSession session =
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new TableSessionBuilder()
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.nodeUrls(Collections.singletonList("127.0.0.1:6667"))
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.username("root")
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.password("root")
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.build()) {
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session.executeNonQueryStatement("CREATE DATABASE db1");
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session.executeNonQueryStatement("use db1");
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// Insert data without manually creating the table
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List<String> columnNameList =
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Arrays.asList("region_id", "plant_id", "device_id", "model", "temperature", "humidity");
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List<TSDataType> dataTypeList =
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Arrays.asList(
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TSDataType.STRING,
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TSDataType.STRING,
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TSDataType.STRING,
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TSDataType.STRING,
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TSDataType.FLOAT,
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TSDataType.DOUBLE);
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List<ColumnCategory> columnTypeList =
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new ArrayList<>(
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Arrays.asList(
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ColumnCategory.TAG,
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ColumnCategory.TAG,
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ColumnCategory.TAG,
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ColumnCategory.ATTRIBUTE,
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ColumnCategory.FIELD,
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ColumnCategory.FIELD));
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Tablet tablet = new Tablet("table1", columnNameList, dataTypeList, columnTypeList, 100);
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for (long timestamp = 0; timestamp < 100; timestamp++) {
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int rowIndex = tablet.getRowSize();
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tablet.addTimestamp(rowIndex, timestamp);
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tablet.addValue("region_id", rowIndex, "1");
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tablet.addValue("plant_id", rowIndex, "5");
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tablet.addValue("device_id", rowIndex, "3");
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tablet.addValue("model", rowIndex, "A");
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tablet.addValue("temperature", rowIndex, 37.6F);
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tablet.addValue("humidity", rowIndex, 111.1);
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if (tablet.getRowSize() == tablet.getMaxRowNumber()) {
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session.insert(tablet);
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tablet.reset();
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}
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}
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if (tablet.getRowSize() != 0) {
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session.insert(tablet);
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tablet.reset();
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}
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}
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```
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After execution, you can verify the table creation using the following command:
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```SQL
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desc table1;
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```
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```shell
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+-----------+---------+-----------+
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| ColumnName| DataType| Category|
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+-----------+---------+-----------+
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| time|TIMESTAMP| TIME|
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| region_id| STRING| TAG|
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| plant_id| STRING| TAG|
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| device_id| STRING| TAG|
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| model| STRING| ATTRIBUTE|
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|temperature| FLOAT| FIELD|
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| humidity| DOUBLE| FIELD|
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+-----------+---------+-----------+
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```
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### 1.3 Specified Column Insertion
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### 1.2 Specified Column Insertion
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It is possible to insert data for specific columns. Columns not specified will remain `null`.
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INSERT INTO table1(region, plant_id, device_id, time, temperature) VALUES ('Hamburg', '1001', '100', '2025-11-26 13:38:00', 91.0);
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```
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### 1.4 Null Value Insertion
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### 1.3 Null Value Insertion
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You can explicitly set `null` values for tag columns, attribute columns, and field columns.
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> **Note:** This operation will not only automatically populate existing tag columns in the table with `null` values but will also populate any newly added tag columns with `null` values in the future.
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### 1.5 Multi-Row Insertion
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### 1.4 Multi-Row Insertion
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IoTDB supports inserting multiple rows of data in a single statement to improve efficiency.
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- Data type mismatches between the insertion data and the column's data type will result in an error code `DATA_TYPE_MISMATCH(614)`.
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### 1.6 Query Write-back
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### 1.5 Query Write-back
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The IoTDB table model supports the **append-only query write-back** feature, implemented via the `INSERT INTO QUERY` statement. This feature allows writing the results of a query into an **existing** table.
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> ​**Note**​: This feature is available starting from version V2.0.6.
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#### 1.6.1 Syntax Definition
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#### 1.5.1 Syntax Definition
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sql
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It costs 0.014s
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```
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#### 1.6.2 Notes
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#### 1.5.2 Notes
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* The source table in the `query` and the target table `table_name` are allowed to be the same table, e.g., `INSERT INTO testtb SELECT * FROM testtb`.
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* The target table ​**must already exist**​; otherwise, the error message `550: Table 'xxx.xxx' does not exist` will be thrown.
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* For more details about user permissions, refer to [Authority Management](../User-Manual/Authority-Management_apache.md).
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## 2. Data Updates
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## 2. Schema-less Writing
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When performing data writing through Session, IoTDB supports schema-less writing: there is no need to manually create tables beforehand. The system automatically constructs the table structure based on the information in the write request, and then directly executes the data writing operation.
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**Example:**
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```Java
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try (ITableSession session =
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new TableSessionBuilder()
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.nodeUrls(Collections.singletonList("127.0.0.1:6667"))
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.username("root")
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.password("root")
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.build()) {
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session.executeNonQueryStatement("CREATE DATABASE db1");
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session.executeNonQueryStatement("use db1");
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// Insert data without manually creating the table
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List<String> columnNameList =
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Arrays.asList("region_id", "plant_id", "device_id", "model", "temperature", "humidity");
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List<TSDataType> dataTypeList =
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Arrays.asList(
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TSDataType.STRING,
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TSDataType.STRING,
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TSDataType.STRING,
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TSDataType.STRING,
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TSDataType.FLOAT,
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TSDataType.DOUBLE);
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List<ColumnCategory> columnTypeList =
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new ArrayList<>(
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Arrays.asList(
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ColumnCategory.TAG,
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ColumnCategory.TAG,
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ColumnCategory.TAG,
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ColumnCategory.ATTRIBUTE,
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ColumnCategory.FIELD,
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ColumnCategory.FIELD));
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Tablet tablet = new Tablet("table1", columnNameList, dataTypeList, columnTypeList, 100);
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for (long timestamp = 0; timestamp < 100; timestamp++) {
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int rowIndex = tablet.getRowSize();
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tablet.addTimestamp(rowIndex, timestamp);
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tablet.addValue("region_id", rowIndex, "1");
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tablet.addValue("plant_id", rowIndex, "5");
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tablet.addValue("device_id", rowIndex, "3");
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tablet.addValue("model", rowIndex, "A");
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tablet.addValue("temperature", rowIndex, 37.6F);
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tablet.addValue("humidity", rowIndex, 111.1);
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if (tablet.getRowSize() == tablet.getMaxRowNumber()) {
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session.insert(tablet);
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tablet.reset();
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}
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}
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if (tablet.getRowSize() != 0) {
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session.insert(tablet);
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tablet.reset();
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}
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}
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```
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After execution, you can verify the table creation using the following command:
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```SQL
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desc table1;
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```
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```shell
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+-----------+---------+-----------+
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| ColumnName| DataType| Category|
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+-----------+---------+-----------+
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| time|TIMESTAMP| TIME|
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| region_id| STRING| TAG|
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| plant_id| STRING| TAG|
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| device_id| STRING| TAG|
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| model| STRING| ATTRIBUTE|
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|temperature| FLOAT| FIELD|
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| humidity| DOUBLE| FIELD|
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+-----------+---------+-----------+
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```
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## 3. Data Updates
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### 2.1 Syntax
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### 3.1 Syntax
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```SQL
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UPDATE <TABLE_NAME> SET updateAssignment (',' updateAssignment)* (WHERE where=booleanExpression)?

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