MyBatis中if - else if - else 的使用

水深无声 2023-01-05 03:54 357阅读 0赞

# [http://www.leftso.com/blog/765.html][http_www.leftso.com_blog_765.html] #

# **不过有他的替代  choose,写法如下：** #

<choose>
                <when test="params!=null">
                    right JOIN
                </when>
                <otherwise>
                    LEFT JOIN
                </otherwise>
            </choose>

复制        <choose>
                <when test="params!=null">
                    right JOIN
                </when>
                <otherwise>
                    LEFT JOIN
                </otherwise>
            </choose>

#    以上即可实现 if else 逻辑 #

# [https://www.cnblogs.com/buzheng/p/12485464.html][https_www.cnblogs.com_buzheng_p_12485464.html] #

# [MyBatis中if - else if - else 的使用][https_www.cnblogs.com_buzheng_p_12485464.html] #

### 有表user（id, name, state, sex, age） ###

### 1、单个 if - else 使用。 ###

根据状态不同进行查询

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

<select id="selectUserByState" resultType="com.bz.model.entity.User">
        SELECT
          *
        FROM
          user
        WHERE
          1=1
        <choose>
          <when test="state == 1">
            AND name = #{name1}
          </when>
          <otherwise>
            AND name = #{name2}
          </otherwise>
        </choose>
      </select>

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

### 2、多个if -else if -else的使用。 ###

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

<select id="selectUserByState" resultType="com.bz.model.entity.User">
        SELECT
          *
        FROM
          user
        WHERE
          1=1
        <choose>
          <when test="state == 1">
            AND name = #{name1}
          </when>
         <when test="state == 2">
            AND name = #{name2}
          </when>
          <otherwise>
            AND name = #{name3}
          </otherwise>
        </choose>
      </select>

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

如有不对之处希望大家指点。共同进步，谢谢！

![816a446a93193a88d4a7f74ac2e66a7f.png][]

[https://www.cnblogs.com/a8457013/p/8033263.html][https_www.cnblogs.com_a8457013_p_8033263.html]

# [mybatis if-else(写法)][https_www.cnblogs.com_a8457013_p_8033263.html] #

## mybaits 中没有else要用chose when otherwise 代替 ##

范例一

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

<insert id="insertBusinessUserList" parameterType="java.util.List">
        insert into `business_user` (`id` , `user_type` , `user_login` )
        values
        <foreach collection="list" index="index" item="item" separator=",">
            <trim prefix="(" suffix=")" suffixOverrides=",">
                <choose>
                    <when test="item.id != null and item.id !=''">
                        #{item.id,jdbcType=CHAR},
                    </when>
                    <otherwise>
                        '',
                    </otherwise>
                </choose>
                <choose>
                    <when test="item.userType != null and item.userType !=''">
                        #{item.userType,jdbcType=VARCHAR},
                    </when>
                    <otherwise>
                        '',
                    </otherwise>
                </choose>
            </trim>
        </foreach>
    </insert>

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

其中choose为一个整体   
when是if   
otherwise是else

范例二：

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

<select id="selectSelective" resultMap="xxx" parameterType="xxx">
        select
        <include refid="Base_Column_List"/>
        from xxx
        where del_flag=0
        <choose>
            <when test="xxx !=null and xxx != ''">
                and xxx like concat(concat('%', #{xxx}), '%')
            </when>
            <otherwise>
                and xxx like '**%'
            </otherwise>
        </choose>
    </select>

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

**下面就是MyBatis中的if....else...表示方法**

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

分类: [mybatis][]

标签: [mybatis][mybatis 1]

[http_www.leftso.com_blog_765.html]: http://www.leftso.com/blog/765.html
[https_www.cnblogs.com_buzheng_p_12485464.html]: https://www.cnblogs.com/buzheng/p/12485464.html
[48304ba5e6f9fe08f3fa1abda7d326ab.png]: /images/20221119/14c84a48b3cb4fdf9cae5e0adea2584b.png
[816a446a93193a88d4a7f74ac2e66a7f.png]: https://img-blog.csdnimg.cn/img_convert/816a446a93193a88d4a7f74ac2e66a7f.png
[https_www.cnblogs.com_a8457013_p_8033263.html]: https://www.cnblogs.com/a8457013/p/8033263.html
[mybatis]: https://www.cnblogs.com/a8457013/category/1104392.html
[mybatis 1]: https://www.cnblogs.com/a8457013/tag/mybatis/