docs: fix OpenDAL presign RFC link (#3035)

* docs: fix OpenDAL presign RFC link

* docs: document streaming load column list

Author: BohuTANG

docs/cn/developer/20-community/02-rfcs/20220704-presign.md

@@ -71,7 +71,7 @@ MySQL [(none)]> PRESIGN UPLOAD @my_stage/books.csv
 
 `PRESIGN` 将作为语句而不是函数来实现，以便我们可以同时返回 HTTP 方法、headers 和 URL。
 
-大多数工作已通过 Apache OpenDAL presign 完成。
+大多数工作已通过 [Apache OpenDAL presign](https://opendal.apache.org/docs/rust/opendal_core/docs/rfcs/rfc_0413_presign/index.html) 完成。
 
 语法将是：
 
@@ -182,4 +182,4 @@ PRESIGN 's3://bucket/books.csv'
 
 ```sql
 PRESIGN UPLOAD_PART 's3://bucket/books.csv.zst'
-```
+```

docs/cn/guides/20-self-hosted/04-references/http-streaming-load.md

@@ -32,11 +32,27 @@ HTTP Streaming Load 是一个专门用来“边传边导入”的接口：服务
 **SQL 结构（必需）：**
 
 ```sql
-INSERT INTO <db>.<table>
+INSERT INTO <db>.<table>[(<col1>, <col2>, ...)]
+[(VALUES (<expr_or_?>, ...))]
 FROM @_databend_load
 FILE_FORMAT=(type=<format> [<options>...])
 ```
 
+### 指定目标列与 `VALUES`
+
+你可以：
+
+- 指定写入的目标列：`INSERT INTO t(col1, col2, ...) ...`
+- 在 `FROM` 前写 `VALUES (...)`：
+  - 用 `?` 表示从上传文件中读取的字段（按顺序对应）。
+  - `?` 可以与常量混用。
+
+示例（从 CSV 读取两列，并补一个常量列）：
+
+```text
+X-Databend-SQL: insert into demo.people(name,age,city) values (?, ?, 'BJ') from @_databend_load file_format=(type=csv skip_header=1)
+```
+
 **cURL 模板：**
 
 ```shell
@@ -144,7 +160,7 @@ EOF
 
 ```shell
 curl -sS -u databend:databend \
-  -H "X-Databend-SQL: insert into demo.people from @_databend_load file_format=(type=csv field_delimiter=',' skip_header=1)" \
+  -H "X-Databend-SQL: insert into demo.people(id,name,age) from @_databend_load file_format=(type=csv field_delimiter=',' skip_header=1)" \
   -F "upload=@./people.csv" \
   -X PUT "http://localhost:8000/v1/streaming_load"
 ```

docs/en/developer/20-community/02-rfcs/20220704-presign.md

@@ -71,7 +71,7 @@ MySQL [(none)]> PRESIGN UPLOAD @my_stage/books.csv
 
 `PRESIGN` will be implemented as a statement instead of a function so that we can return the HTTP method, headers, and URL at the same time.
 
-Most jobs have been done via Apache OpenDAL presign.
+Most jobs have been done via [Apache OpenDAL presign](https://opendal.apache.org/docs/rust/opendal_core/docs/rfcs/rfc_0413_presign/index.html).
 
 The syntax will be:
 

docs/en/guides/20-self-hosted/04-references/http-streaming-load.md

@@ -32,11 +32,27 @@ It is useful when you:
 **SQL format (required):**
 
 ```sql
-INSERT INTO <db>.<table>
+INSERT INTO <db>.<table>[(<col1>, <col2>, ...)]
+[(VALUES (<expr_or_?>, ...))]
 FROM @_databend_load
 FILE_FORMAT=(type=<format> [<options>...])
 ```
 
+### Specifying columns and using `VALUES`
+
+You can:
+
+- Specify the target columns: `INSERT INTO t(col1, col2, ...) ...`
+- Provide `VALUES (...)` before `FROM`:
+  - Use `?` as placeholders for fields read from the uploaded file (in order).
+  - Mix `?` with constants.
+
+Example (load two columns from a CSV file and set a constant):
+
+```text
+X-Databend-SQL: insert into demo.people(name,age,city) values (?, ?, 'BJ') from @_databend_load file_format=(type=csv skip_header=1)
+```
+
 **cURL template:**
 
 ```shell
@@ -155,7 +171,7 @@ Send a `PUT /v1/streaming_load` request:
 
 ```shell
 curl -sS -u databend:databend \
-  -H "X-Databend-SQL: insert into demo.people from @_databend_load file_format=(type=csv field_delimiter=',' skip_header=1)" \
+  -H "X-Databend-SQL: insert into demo.people(id,name,age) from @_databend_load file_format=(type=csv field_delimiter=',' skip_header=1)" \
   -F "upload=@./people.csv" \
   -X PUT "http://localhost:8000/v1/streaming_load"
 ```