---
{
    "title": "UPDATE",
    "language": "zh-CN"
}
---

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# UPDATE
## description
### Syntax

```
UPDATE table_name 
    SET assignment_list
    WHERE expression

value:
    {expr | DEFAULT}

assignment:
    col_name = value

assignment_list:
    assignment [, assignment] ...
```

### Parameters

+ table_name: 待更新数据的目标表。可以是 'db_name.table_name' 形式
+ assignment_list: 待更新的目标列，形如 'col_name = value, col_name = value' 格式
+ where expression: 期望更新的条件，一个返回 true 或者 false 的表达式即可

### Note

当前 UPDATE 语句仅支持在 Unique 模型上的行更新，存在并发更新导致的数据冲突可能。
目前 Doris 并不处理这类问题，需要用户从业务侧规避这类问题。

## example

`test` 表是一个 unique 模型的表，包含: k1, k2, v1, v2  四个列。其中 k1, k2 是 key，v1, v2 是value，聚合方式是 Replace。

1. 将 'test' 表中满足条件 k1 =1 , k2 =2 的 v1 列更新为 1

```
UPDATE test SET v1 = 1 WHERE k1=1 and k2=2;
```

2. 将 'test' 表中 k1=1 的列的 v1 列自增1

```
UPDATE test SET v1 = v1+1 WHERE k1=1;
```

## keyword

    UPDATE