# URL_DECODE
#### 语法
```
VARCHAR URL_DECODE(VARCHAR input)
VARCHAR URL_DECODE(VARCHAR input, VARCHAR encoding)
```
#### 描述
URL_DECODE函数用于将application/x-www-form-urlencodedMIME格式的输入字符串转换为标准字符串。
#### 约束与限制
本章节仅适用于MRS 3.6.0-LTS.1及之后版本。
#### 入参
| 参数       | 数据类型    | **说明**                                               |
|:---|:---|:---|
| input    | VARCHAR | 该参数指定要输入的字符串。                                        |
| encoding | VARCHAR | 可选参数，此参数用于指定解码格式，可以是GBK或者UTF-8等，如果不指定此参数则使用默认值UTF-8。 |
   
#### 示例
```
CREATE TABLE source (
  f_sequence INT
) WITH (
  'connector' = 'datagen',
  'rows-per-second' = '1'
);
create TABLE print with(
'connector' = 'print'
)as select
  URL_DECODE ('http://calcite.apache.org') as value1,
  URL_DECODE ('https%3A%2F%2Fcalcite.apache.org') as value2,
  URL_DECODE ('http%3A%2F%2Ftest%3Fa%3Db%26c%3Dd') as value3,
  URL_DECODE ('http%3A%2F%2F%E4%BD%A0%E5%A5%BD') as value4,
  URL_DECODE ('test') as value5,
  URL_DECODE ('https%%3A%2F%2Fcalcite.apache.org') as value6,
  URL_DECODE ('https%3A%2F%2Fcalcite.apache.org%','UTF-8') as value7,
  URL_DECODE ('https%3A%2F%2Fcalcite.apache.org', 'gb2312') as value8
from source;
```
表1返回结果 
| **value1(VARCHAR)**       | **value2(VARCHAR)**       | **value3(VARCHAR)**  | **value4(VARCHAR**) | **value5(VARCHAR)** | **value6(VARCHAR)** | **value7(VARCHAR)** | **value8(VARCHAR**)        |
|:---|:---|:---|:---|:---|:---|:---|:---|
| http://calcite.apache.org | http://calcite.apache.org | http://test?a=b\&c=d | http://你好           | test                | null                | null                | https://calcite.apache.org |