---
title: "XMLCAST - OceanBase 数据库 V4.5.0 | OceanBase 文档中心"
description: XMLCAST 描述 该函数用于抽取 XML 文档的内容（不包括元素名称），并将其转换为 CHAR 、 VARCHAR 、 VARCHAR2 、 NUMBER 、 FLOAT 、 BLOB 或 CLOB 及任何日期时间数据类型。 语法 XMLCAST ( value_expression AS datatype ) …
---
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# XMLCAST
更新时间：2026-03-09 08:20:17
[编辑](https://github.com/oceanbase/oceanbase-doc/edit/V4.5.0/zh-CN/700.reference/500.sql-reference/100.sql-syntax/300.common-tenant-of-oracle-mode/500.functions-of-oracle-mode/200.single-row-functions-of-oracle-mode/1300.xml-functions-of-oracle-mode/300.querying-xmltype-data-functions-of-oracle-mode/400.xmlcast-function-of-oracle-mode.md)
## 描述
该函数用于抽取 XML 文档的内容（不包括元素名称），并将其转换为 `CHAR`、`VARCHAR`、`VARCHAR2`、`NUMBER`、`FLOAT`、`BLOB` 或 `CLOB` 及任何日期时间数据类型。
## 语法
```sql
XMLCAST ( value_expression AS datatype )
```
## 参数解释
| 字段 | 说明 |
| --- | --- |
| value_expression | 指定解析的内容必须为一个有效的 XML 片段。 |
| AS datatype | 指定返回的类型，可以为 `CHAR`、`VARCHAR`、`VARCHAR2`、`NUMBER`、`FLOAT`、`BLOB` 或 `CLOB` 及任何日期时间数据类型。 |
## 返回类型
返回 `CHAR`、`VARCHAR`、`VARCHAR2`、`NUMBER`、`FLOAT`、`BLOB` 或 `CLOB` 及任何日期时间数据类型。
## 示例
```shell
# 转换为 CHAR
obclient> SELECT XMLCAST(XMLPARSE(DOCUMENT 'a') AS CHAR) FROM DUAL;
+-----------------------------------------------------------------+
| XMLCAST(XMLPARSE(DOCUMENT'A')ASCHAR) |
+-----------------------------------------------------------------+
| a |
+-----------------------------------------------------------------+
1 row in set
# 转换为 VARCHAR2
obclient> SELECT XMLCAST(XMLPARSE(DOCUMENT 'aaaaaa') AS VARCHAR2(5)) FROM DUAL;
+-----------------------------------------------------------------------------+
| XMLCAST(XMLPARSE(DOCUMENT'AAAAAA')ASVARCHAR2(5)) |
+-----------------------------------------------------------------------------+
| aaaaa |
+-----------------------------------------------------------------------------+
1 row in set
# 转换为 BLOB
obclient> SELECT XMLCAST(XMLPARSE(DOCUMENT '123f') AS BLOB) FROM DUAL;
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| XMLCAST(XMLPARSE(DOCUMENT'123F')ASBLOB) |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 123F |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set
# 转换为 CLOB
obclient> SELECT XMLCAST(XMLPARSE(DOCUMENT '
To
Jani
Reminder
Do not forget me this weekend!
') AS CLOB) RES FROM DUAL;
+----------------------------------------------+
| RES |
+----------------------------------------------+
| ToJaniReminderDo not forget me this weekend! |
+----------------------------------------------+
1 row in set
# 转换为 NUMBER
obclient> SELECT XMLCAST(XMLPARSE(CONTENT '123.01') AS NUMBER) FROM DUAL;
+---------------------------------------------------+
| XMLCAST(XMLPARSE(CONTENT'123.01')ASNUMBER) |
+---------------------------------------------------+
| 123.01 |
+---------------------------------------------------+
1 row in set
# 转换为 FLOAT
obclient> SELECT XMLCAST(XMLPARSE(CONTENT '123.01') AS FLOAT) FROM DUAL;
+--------------------------------------------------+
| XMLCAST(XMLPARSE(CONTENT'123.01')ASFLOAT) |
+--------------------------------------------------+
| 123.01 |
+--------------------------------------------------+
1 row in set
# 转换为 DECIMAL
obclient> SELECT XMLCAST(XMLPARSE(CONTENT '123.01') AS DECIMAL) FROM DUAL;
+----------------------------------------------------+
| XMLCAST(XMLPARSE(CONTENT'123.01')ASDECIMAL) |
+----------------------------------------------------+
| 123 |
+----------------------------------------------------+
1 row in set
# 转换为 TIMESTAMP
obclient> SELECT XMLCAST(XMLPARSE(CONTENT '2023-04-01 15:13:00') AS TIMESTAMP) AS RES FROM DUAL;
+----------------------------+
| RES |
+----------------------------+
| 2023-04-01 15:13:00.000000 |
+----------------------------+
1 row in set
# 转换为 DATE
obclient> SELECT XMLCAST(XMLPARSE(CONTENT '2023-04-01 15:13:00') AS DATE) AS RES FROM DUAL;
+---------------------+
| RES |
+---------------------+
| 2023-04-01 15:13:00 |
+---------------------+
1 row in set
# 转换为 INTERVAL YEAR TO MONTH
obclient> SELECT XMLCAST(XMLPARSE(CONTENT '12-3') AS INTERVAL YEAR(3) TO MONTH) AS RES FROM DUAL;
+---------+
| RES |
+---------+
| +012-03 |
+---------+
1 row in set
# 转换为 INTERVAL DAY TO SECOND
obclient> SELECT XMLCAST(XMLPARSE(CONTENT '140 5:12:10.2222222') AS INTERVAL DAY(3) TO SECOND(7)) AS RES FROM DUAL;
+-----------------------+
| RES |
+-----------------------+
| +140 05:12:10.2222222 |
+-----------------------+
1 row in set
```
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