Map<String, Object> getUserToMap(@Param("id") int id);
<select id="getUserToMap" resultType="map"> select * from t_user where id = #{id} </select>
List<Map<String, Object>> getAllUserToMap();
<select id="getAllUserToMap" resultType="map"> select * from t_user </select>
@MapKey("id")
Map<String, Object> getAllUserToMap();
<select id="getAllUserToMap" resultType="map"> select * from t_user </select>
{ 1={password=123456, sex=男, id=1, age=23, username=admin}, 2={password=123456, sex=男, id=2, age=23, username=张三}, 3={password=123456, sex=男, id=3, age=23, username=张三} }
List<User> testMohu(@Param("mohu") String mohu);
<select id="testMohu" resultType="User">
<!--select * from t_user where username like '%${mohu}%'-->
<!--select * from t_user where username like concat('%',#{mohu},'%')-->
select * from t_user where username like "%"#{mohu}"%"
</select>
mapper.deleteMore("1, 2, 3");
int deleteMore(@Param("ids") String ids);
<delete id="deleteMore"> delete from t_user where id in (${ids}) </delete>
List<User> getAllUser(@Param("tableName") String tableName);
<select id="getAllUser" resultType="User"> select * from ${tableName} </select>
//useGeneratedKeys：设置使用自增的主键，keyProperty：因为增删改有统一的返回值是受影响的行数，因此只能将获取的自增的主键放在传输的参 数user对象的某个属性中
int insertUser(User user);
<insert id="insertUser" useGeneratedKeys="true" keyProperty="id">
insert into t_user values(null,#{username},#{password},#{age},#{sex})
</insert>
List<Emp> getAllEmp();
<select id="getAllEmp" resultMap="Emp">
select id, emp_name empName, age from t_emp
</select>
# mybatis配置文件中配置如下
<settings>
<!--将_自动映射为驼峰，emp_name:empName-->
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
# mapper
List<Emp> getAllEmp();
# xml映射
<select id="getAllEmp" resultMap="Emp">
select id, emp_name, age from t_emp
</select>
# mapper
List<Emp> getAllEmp();
# xml映射
<resultMap id="empResultMap" type="Emp">
<id property="eid" column="eid"></id>
<result property="empName" column="emp_name"></result>
<result property="age" column="age"></result>
<result property="sex" column="sex"></result>
<result property="email" column="email"></result>
</resultMap>
<select id="getAllEmp" resultMap="empResultMap">
select id, emp_name, age from t_emp
</select>
# 部门表
public class Dept {
private Integer did;
private String deptName;
//private List<Emp> emps;
@Override
public String toString() {
return "Dept{" +
"did=" + did +
", deptName='" + deptName + '\'' +
//", emps=" + emps +
'}';
}
//public List<Emp> getEmps() {
//return emps;
//}
//public void setEmps(List<Emp> emps) {
//this.emps = emps;
//}
public Integer getDid() {
return did;
}
public void setDid(Integer did) {
this.did = did;
}
public String getDeptName() {
return deptName;
}
public void setDeptName(String deptName) {
this.deptName = deptName;
}
public Dept() {
}
public Dept(Integer did, String deptName) {
this.did = did;
this.deptName = deptName;
}
}
# 员工表，添加部门对象作为属性，编写getter方法和setter方法，toString方法
public class Emp implements Serializable {
private Integer eid;
private String empName;
private Integer age;
private String sex;
private String email;
private Dept dept;
@Override
public String toString() {
return "Emp{" +
"eid=" + eid +
", empName='" + empName + '\'' +
", age=" + age +
", sex='" + sex + '\'' +
", email='" + email + '\'' +
", dept=" + dept +
'}';
}
public Dept getDept() {
return dept;
}
public void setDept(Dept dept) {
this.dept = dept;
}
public Integer getEid() {
return eid;
}
public void setEid(Integer eid) {
this.eid = eid;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public Emp() {
}
public Emp(Integer eid, String empName, Integer age, String sex, String email) {
this.eid = eid;
this.empName = empName;
this.age = age;
this.sex = sex;
this.email = email;
}
}
Emp getEmpAndDept(@Param("eid") Integer eid);
<resultMap id="empAndDeptResultMapOne" type="Emp">
<id property="eid" column="eid"></id>
<result property="empName" column="emp_name"></result>
<result property="age" column="age"></result>
<result property="sex" column="sex"></result>
<result property="email" column="email"></result>
<result property="dept.did" column="did"></result>
<result property="dept.deptName" column="dept_name"></result>
</resultMap>
<select id="getEmpAndDept" resultMap="empAndDeptResultMapOne">
select * from t_emp left join t_dept on t_emp.did = t_dept .did where t_emp.eid = #{eid}
</select>
Emp getEmpAndDept(@Param("eid") Integer eid);
<resultMap id="empAndDeptResultMapTwo" type="Emp">
<id property="eid" column="eid"></id>
<result property="empName" column="emp_name"></result>
<result property="age" column="age"></result>
<result property="sex" column="sex"></result>
<result property="email" column="email"></result>
<!--
association:处理多对一的映射关系
property:需要处理多对的映射关系的属性名
javaType:该属性的类型
-->
<association property="dept" javaType="Dept">
<id property="did" column="did"></id>
<result property="deptName" column="dept_name"></result>
</association>
</resultMap>
<select id="getEmpAndDept" resultMap="empAndDeptResultMapOne">
select * from t_emp left join t_dept on t_emp.did = t_dept .did where t_emp.eid = #{eid}
</select>
# 部门mapper
Dept getEmpDeptByStep(@Param("did") int did);
# 部门映射文件，根据部门id查询部门信息
<select id="getEmpDeptByStep" resultType="Dept">
select * from t_dept where did = #{did}
</select>
# 员工mapper
Emp getEmpByStep(@Param("eid") int eid);
# 员工映射文件
<resultMap id="empDeptStepMap" type="Emp">
<id column="eid" property="eid"></id>
<result column="ename" property="ename"></result>
<result column="age" property="age"></result>
<result column="sex" property="sex"></result>
<!--select：设置分步查询，查询某个属性的值的sql的标识（namespace.sqlId） column：将sql以及查询结果中的某个字段设置为分步查询的条件 -->
<association property="dept" select="com.atguigu.MyBatis.mapper.DeptMapper.getEmpDeptByStep" column="did">
</association>
</resultMap>
<select id="getEmpByStep" resultMap="empDeptStepMap">
select * from t_emp where eid = #{eid}
</select>
# lazyLoadingEnabled设置为true，aggressiveLazyLoding设置为false，mybatis版本>=3.4.1时默认为true
<settings>
<setting name="lazyLoadingEnabled" value="true"/>
</settings>
# 部门表，添加员工对象，并添加getter和setter方法，toString方法
public class Dept {
private Integer did;
private String deptName;
private List<Emp> emps;
@Override
public String toString() {
return "Dept{" +
"did=" + did +
", deptName='" + deptName + '\'' +
", emps=" + emps +
'}';
}
public List<Emp> getEmps() {
return emps;
}
public void setEmps(List<Emp> emps) {
this.emps = emps;
}
public Integer getDid() {
return did;
}
public void setDid(Integer did) {
this.did = did;
}
public String getDeptName() {
return deptName;
}
public void setDeptName(String deptName) {
this.deptName = deptName;
}
public Dept() {
}
public Dept(Integer did, String deptName) {
this.did = did;
this.deptName = deptName;
}
}
# mapper
Dept getDeptEmpByDid(@Param("did") int did);
# xml，配置返回结果集，根据部门id查询数据
<resultMap id="deptEmpMap" type="Dept">
<id property="did" column="did"></id>
<result property="dname" column="dname"></result>
<!--ofType：设置collection标签所处理的集合属性中存储数据的类型 -->
<collection property="emps" ofType="Emp">
<id property="eid" column="eid"></id>
<result property="ename" column="ename"></result>
<result property="age" column="age"></result>
<result property="sex" column="sex"></result>
</collection>
</resultMap>
<select id="getDeptEmpByDid" resultMap="deptEmpMap">
select dept.*,emp.* from t_dept dept left join t_emp emp on dept.did = emp.did where dept.did = #{did}
</select>
# 部门mapper
Dept getDeptByStep(@Param("did") int did);
# 部门xml，根据部门id查询数据
<resultMap id="deptEmpStep" type="Dept">
<id property="did" column="did"></id>
<result property="dname" column="dname"></result>
<collection property="emps" fetchType="eager" select="com.atguigu.MyBatis.mapper.EmpMapper.getEmpListByDid" column="did"></collection>
</resultMap>
<select id="getDeptByStep" resultMap="deptEmpStep">
select * from t_dept where did = #{did}
</select>
# 员工mapper
List<Emp> getEmpListByDid(@Param("did") int did);
# 员工xml，根据员工id查询数据
<select id="getEmpListByDid" resultType="Emp">
select * from t_emp where did = #{did}
</select>
