yiguolei commented on code in PR #4380:
URL: https://github.com/apache/doris-website/pull/4380#discussion_r4323752438
##########
i18n/zh-CN/docusaurus-plugin-content-docs/current/sql-manual/basic-element/sql-data-types/conversion/file-conversion.md:
##########
@@ -0,0 +1,180 @@
+---
+{
+ "title": "转换为/从 FILE",
+ "language": "zh-CN",
+ "description": "FILE 与 STRUCT、JSON、VARIANT 的显式双向转换及 NULL 处理规则。"
+}
+---
+
+# 转换为/从 FILE
+
+FILE 支持与 STRUCT、JSON、VARIANT 显式双向转换。**FILE 与这些类型之间不支持隐式转换，须使用 CAST。**
转换本身不访问远端存储，字段定义及取值约束见 [FILE](../semi-structured/FILE.md)。
+
+## 转换为 FILE
+
+### FROM STRUCT
+
+源 STRUCT 须包含完整六字段，按名称匹配，不区分大小写，字段顺序可不同。offset 和 size 须为 BIGINT 或 NULL，inline
须为 VARBINARY 或 NULL，文本字段须为 CHAR/VARCHAR/STRING 或 NULL。未知、缺失、重复或类型不兼容的字段会被拒绝。
+
+```sql
+SELECT CAST(NAMED_STRUCT(
+ 'uri', 's3://linrrzqqq/doris-file-type-test/my-github-avatar.jpg',
'offset', NULL, 'size', CAST(3 AS BIGINT),
+ 'content_type', NULL, 'checksum', NULL, 'inline', X'616263'
+) AS FILE) AS f;
+```
+```text
++-----------------------------------------------------------------------------------------------------------+
+| f
|
++-----------------------------------------------------------------------------------------------------------+
+|
{"uri":"s3://linrrzqqq/doris-file-type-test/my-github-avatar.jpg","offset":null,"size":3,"content_type":null,"checksum":null,"inline":"YWJj"}
|
++-----------------------------------------------------------------------------------------------------------+
+```
+
+### FROM JSON
+
+JSON 对象须恰好包含 uri、offset、size、content_type、checksum、inline 六个小写 key。offset 和
size 接受 BIGINT 范围的 JSON 整数或 null；inline 接受标准、带 padding 的 Base64 字符串或
null，空字符串表示空字节序列。
+
+```sql
+SELECT CAST(JSON_PARSE(
+
'{"uri":"s3://linrrzqqq/doris-file-type-test/my-github-avatar.jpg","offset":null,"size":3,"content_type":null,"checksum":null,"inline":"YWJj"}'
+) AS FILE) AS f;
+```
+```text
++-----------------------------------------------------------------------------------------------------------+
+| f
|
++-----------------------------------------------------------------------------------------------------------+
+|
{"uri":"s3://linrrzqqq/doris-file-type-test/my-github-avatar.jpg","offset":null,"size":3,"content_type":null,"checksum":null,"inline":"YWJj"}
|
++-----------------------------------------------------------------------------------------------------------+
+```
+
+### FROM VARIANT
+
+对象形式的 VARIANT 使用与 JSON 相同的字段名、字段类型及 Base64 表示。
+
+```sql
+SELECT CAST(PARSE_TO_VARIANT(
+
'{"uri":"s3://linrrzqqq/doris-file-type-test/my-github-avatar.jpg","offset":null,"size":3,"content_type":null,"checksum":null,"inline":"YWJj"}'
+) AS FILE) AS f;
+```
+```text
++-----------------------------------------------------------------------------------------------------------+
+| f
|
++-----------------------------------------------------------------------------------------------------------+
+|
{"uri":"s3://linrrzqqq/doris-file-type-test/my-github-avatar.jpg","offset":null,"size":3,"content_type":null,"checksum":null,"inline":"YWJj"}
|
++-----------------------------------------------------------------------------------------------------------+
+```
+
+### FROM NULL
+
+SQL NULL 和 JSON null 可显式转换为 NULL FILE。
+
+```sql
+SELECT CAST(NULL AS FILE) AS f;
+```
+```text
++------+
+| f |
++------+
+| NULL |
++------+
+```
+
+## 从 FILE 转换
+
+### TO STRUCT
+
+目标 STRUCT 须包含完整六字段，按名称匹配，不区分大小写。各字段均须允许 NULL：uri、content_type、checksum
使用字符串类型，offset 和 size 使用 BIGINT，inline 使用 VARBINARY。转换保留 inline 原始二进制内容。
+
+```sql
+SELECT CAST(f AS STRUCT<uri:STRING, offset:BIGINT, size:BIGINT,
+ content_type:STRING, checksum:STRING, inline:VARBINARY>) AS s
+FROM (SELECT CAST(NAMED_STRUCT(
+ 'uri', 's3://linrrzqqq/doris-file-type-test/my-github-avatar.jpg',
'offset', NULL, 'size', CAST(3 AS BIGINT),
+ 'content_type', NULL, 'checksum', NULL, 'inline', X'616263'
+) AS FILE) AS f) t;
+```
+```text
++------------------------------------------------------------------------------------------------------------------+
+| s
|
++------------------------------------------------------------------------------------------------------------------+
+| {"uri":"s3://linrrzqqq/doris-file-type-test/my-github-avatar.jpg",
"offset":null, "size":3, "content_type":null, "checksum":null,
"inline":0x616263} |
++------------------------------------------------------------------------------------------------------------------+
+```
+
+### TO JSON
Review Comment:
这些to json 之类的也不支持了
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