标签：字符串 open ddr 生日 开始 属性 mes 基本 poj
<!-- namespace:命名空间，用于隔离sql，类似java的包 -->
<!-- #{}:点位符，相当于jdbc的? -->
<!-- ${}：字符串拼接指令，如果入参为普通数据类型时，{}里只能写value -->
<!-- 动态代理开发规则：
1. namespace必需是接口的全路径名
2. 接口的方法名必需与映射文件的sql id一致
3. 接口的输入参数必需与映射文件的parameterType类型一致
4. 接口的返回类型必须与映射文件的resultType类型一致
-->
<resultMap type="com.itheima.mybatis.pojo.Order" id="order_map"> <!-- 用<id>映射主键 --> <id property="id" column="id"/> <!-- 普通字段用<result>映射 --> <result property="userId" column="user_id"/> <!-- 单表查询下，字段与属性一致时可以省略 --> <!-- <result property="number" column="number"/> <result property="createtime" column="createtime"/> <result property="note" column="note"/> --> </resultMap> <!-- resultMap的使用 --> <select id="getOrderListResultMap" resultMap="order_map"> SELECT `id`, `user_id`, `number`, `createtime`, `note` FROM `order` </select>
<!-- 定义sql片段 -->
<sql id="user_sql">
`id`,
`username`,
`birthday`,
`sex`,
`address`
</sql>
<!-- parameterType:入参的数据类型
resultType:返回结果的数据类型
-->
<!-- 别名的使用，不区分大小写 -->
<select id="getUserById" parameterType="int" resultType="uSEr">
SELECT
<include refid="user_sql"/>
FROM `user`
WHERE id = #{id}
</select>
<!-- resultType:返回为集合时，只需设置为其中一个元素的数据类型就可 -->
<select id="getUserByUserName" parameterType="string" resultType="com.itheima.mybatis.pojo.User">
SELECT
`id`,
`username`,
`birthday`,
`sex`,
`address`
FROM `user`
<!-- WHERE username LIKE #{name} -->
<!-- -->
WHERE username LIKE ‘%${value}%‘
</select>
<!-- resultType:返回为集合时，只需设置为其中一个元素的数据类型就可 -->
<select id="getUserByWhere" parameterType="user" resultType="com.itheima.mybatis.pojo.User">
SELECT
<include refid="user_sql"/>
FROM `user`
<!-- WHERE 1 = 1
<if test="username != null and username != ‘‘">
and username LIKE ‘%${username}%‘
</if>
<if test="sex != null and sex != ‘‘">
and sex = #{sex}
</if> -->
<!-- <where>会自动添加where关键字，同时处理多余的and -->
<where>
<if test="username != null and username != ‘‘">
and username LIKE ‘%${username}%‘
</if>
<if test="sex != null and sex != ‘‘">
and sex = #{sex}
</if>
</where>
</select>
public class QueryVo {
private User user;
private List<Integer> ids;
//..省略get和set方法
}
<select id="getUserByIds" parameterType="queryvo" resultType="user">
SELECT
`id`,
`username`,
`birthday`,
`sex`,
`address`,
`uuid2`
FROM `user`
<!-- WHERE id IN(1,10,25,30,32) -->
<if test="ids != null">
<where>
<!-- collection:要遍历的集合，在这里就是pojo的id列表
open:循环开始之前输出的内容
close:循环结束之后输出的内容
item:每次循环的变量
separator:分隔符
-->
<foreach collection="ids" open="id IN(" close=")" item="u_id" separator=",">
#{u_id}
</foreach>
</where>
</if>
</select>
public class Order {
private Integer id;
private Integer userId;
private String number;
private Date createtime;
private String note;
private User user;
//..省略get和set
}
public class OrderUser extends Order {
private String username;
private String address;
//..省略get和set
}
//方式一查询
<select id="getOrderUser" resultType="orderUser">
SELECT
o.`id`,
o.`user_id`,
o.`number`,
o.`createtime`,
o.`note`,
u.`username`,
u.`address`
FROM
`order` o
LEFT JOIN `user` u
ON u.`id` = o.`user_id`
</select>
//方式二查询用association
<resultMap type="order" id="order_user_map">
<!-- 用<id>映射主键 -->
<id property="id" column="id"/>
<!-- 普通字段用<result>映射 -->
<result property="userId" column="user_id"/>
<!-- 单表查询下，字段与属性一致时可以省略 -->
<result property="number" column="number"/>
<result property="createtime" column="createtime"/>
<result property="note" column="note"/>
<!-- 一对一关联查询用association
property:关联的属性，在这里就是订单的用户属性
javaType:user属性的数据类型，支持别名
-->
<association property="user" javaType="com.itheima.mybatis.pojo.User">
<!-- 用<id>映射主键 -->
<id property="id" column="user_id"/>
<!-- 普通字段用<result>映射 -->
<result property="username" column="username"/>
<result property="address" column="address"/>
<result property="birthday" column="birthday"/>
<result property="sex" column="sex"/>
</association>
</resultMap>
<select id="getOrderUserResultMap" resultMap="order_user_map">
SELECT
o.`id`,
o.`user_id`,
o.`number`,
o.`createtime`,
o.`note`,
u.`username`,
u.`address`,
u.`birthday`,
u.`sex`
FROM
`order` o
LEFT JOIN `user` u
ON u.`id` = o.`user_id`
</select>
public class User {
private Integer id;
private String username;// 用户姓名
private String sex;// 性别
private Date birthday;// 生日
private String address;// 地址
private String uuid2;
private List<Order> orders;
//..省略get和set
}
//第一种方法
<!-- resultType:返回为集合时，只需设置为其中一个元素的数据类型就可 -->
<select id="getUserByQueryVo" parameterType="queryvo" resultType="com.itheima.mybatis.pojo.User">
SELECT
`id`,
`username`,
`birthday`,
`sex`,
`address`
FROM `user`
<!-- WHERE username LIKE #{name} -->
<!-- -->
WHERE username LIKE ‘%${user.username}%‘
</select>
//第二种方法是用标签collection
<resultMap type="user" id="user_order_map">
<!-- 用<id>映射主键 -->
<id property="id" column="id"/>
<!-- 普通字段用<result>映射 -->
<result property="username" column="username"/>
<result property="address" column="address"/>
<result property="birthday" column="birthday"/>
<result property="sex" column="sex"/>
<!-- 一对多关联用<collection>
property:属性名称
ofType:属性的数据类型
-->
<collection property="orders" ofType="order">
<id property="id" column="o_id"/>
<!-- 普通字段用<result>映射 -->
<result property="userId" column="id"/>
<!-- 单表查询下，字段与属性一致时可以省略 -->
<result property="number" column="number"/>
<result property="createtime" column="createtime"/>
<result property="note" column="note"/>
</collection>
</resultMap>
<select id="getUserOrderMap" resultMap="user_order_map">
SELECT
u.`id`,
u.`username`,
u.`birthday`,
u.`sex`,
u.`address`,
u.`uuid2`,
o.`id` o_id,
o.`number`,
o.`createtime`,
o.`note`
FROM
`user` u
LEFT JOIN `order` o
ON o.`user_id` = u.`id`
</select>
<insert id="insertUser" parameterType="User">
INSERT INTO USER
(`username`,
`birthday`,
`sex`,
`address`)
VALUES (#{username},
#{birthday},
#{sex},
#{address});
</insert>
<delete id="deleteUser" parameterType="int">
DELETE FROM `user` WHERE `id` = #{id1}
</delete>
<update id="updateUser" parameterType="User"> UPDATE USER SET username = #{username} WHERE id = #{id} </update>
标签：字符串 open ddr 生日 开始 属性 mes 基本 poj
原文地址：https://www.cnblogs.com/liushisaonian/p/9557368.html
