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Update question.mdx #396

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36 changes: 27 additions & 9 deletions src/content/docs/reference/question.mdx
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Original file line number Diff line number Diff line change
Expand Up @@ -274,7 +274,7 @@ FieldStrategy 有三种策略：
.set(User::getEmail, null) //把email设置成null
.eq(User::getId, 2)
);

```

</Accordion>
Expand Down Expand Up @@ -366,16 +366,19 @@ public interface DataResourceMapper extends BaseMapper<DataResource>{}
</Accordion>


<Accordion client:load title={'`Cause: org.apache.ibatis.type.TypeException:Error setting null for parameter #1 with JdbcType OTHER`'}>
<Accordion client:load title={'Cause: org.apache.ibatis.type.TypeException:Error setting null for parameter #1 with JdbcType OTHER . Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. Cause: java.sql.SQLException: 无效的列类型: 1111'}>
在 MyBatis-Plus 中, `jdbcTypeForNull` 是一个重要的配置选项, 它决定了如何将Java的 `null` 值映射到数据库中.

默认情况下, 当某个字段在 Java 中为 `null` 时, MyBatis-Plus 会将其映射为数据库中的 `JdbcType.OTHER` 值。但某些 JDBC 驱动程序 (例如 Oracle) 不支持 `JdbcType.OTHER` ，因此默认设置会导致错误: `Cause: org.apache.ibatis.type.TypeException:Error setting null for parameter #1 with JdbcType OTHER . Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. Cause: java.sql.SQLException: 无效的列类型: 1111`.

> 配置 jdbcTypeForNull=NULL
> Spring Bean 配置方式：
要设置 `jdbcTypeForNull` , 你需要在 MyBatis-Plus 的配置类中添加以下代码:

> Spring Bean 配置

```java
MybatisConfiguration configuration = new MybatisConfiguration();
configuration.setDefaultScriptingLanguage(MybatisXMLLanguageDriver.class);
configuration.setJdbcTypeForNull(JdbcType.NULL);
configuration.setMapUnderscoreToCamelCase(true);//开启下划线转驼峰
sqlSessionFactory.setConfiguration(configuration);
```

Expand All @@ -386,6 +389,21 @@ mybatis-plus:
jdbc-type-for-null: 'null'
```

> properties 配置
```properties
mybatis-plus.configuration.jdbc-type-for-null=NULL
```

> XML 配置
```XML
<configuration>
<settings>
<setting name="jdbcTypeForNull" value="NULL" />
</settings>
</configuration>
```

> 需要注意的是, 如果你在项目中自定义 `SqlSessionFactory` 可能导致 `jdbc-type-for-null` 配置失效.
</Accordion>


Expand Down Expand Up @@ -526,7 +544,7 @@ There is one backward incompatible changes since 3.5.0.

解决方案：
1. 将 Spring Boot 降级至 2.1.x 版本，或升级至 2.2.1 版本以上。建议直接升级至 Spring Boot 2.2.2 版本以获取更好的稳定性和修复。


</Accordion>

Expand Down Expand Up @@ -555,7 +573,7 @@ There is one backward incompatible changes since 3.5.0.
mybatis-plus:
configuration:
# 如果项目无日志框架，可以考虑指定为 org.apache.ibatis.logging.stdout.StdOutImpl (请勿在实际生产中使用).
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
```

这将使用 MyBatis 内置的 StdOutImpl 日志记录实现将日志输出到控制台。
Expand Down Expand Up @@ -638,7 +656,7 @@ mybatis-plus:

```xml
<select id="selectAllNames" resultType="java.lang.String">
select
select
<choose>
<when test="_databaseId == 'mysql'">
GROUP_CONCAT(name SEPARATOR ',')
Expand Down Expand Up @@ -701,7 +719,7 @@ MyBatis Plus 不支持复合主键并强制使用唯一的 ID，这是出于以

碰到过使用hikari在linux系统下启动缓慢

解决方案:
解决方案:

在java启动命令中指定 -Djava.security.egd=file:/dev/urandom把获取随机数的方式从 /dev/random改为/dev/urandom

Expand Down