Mybatis——动态SQL详解
动态SQL
bean:
public class Department {
private Integer id;
private String departmentName;
private List emps;
public Department(Integer id) {
super();
this.id = id;
}
public Department() {
super();
// TODO Auto-generated constructor stub
}
public List getEmps() {
return emps;
}
public void setEmps(List emps) {
this.emps = emps;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getDepartmentName() {
return departmentName;
}
public void setDepartmentName(String departmentName) {
this.departmentName = departmentName;
}
@Override
public String toString() {
return "Department [id=" + id + ", departmentName=" + departmentName + "]";
}
} public class Employee {
private Integer id;
private String last_name;
private String email;
private String gender;
private Department department;
public Employee(Integer id, String last_name, String email, String gender, Department department) {
super();
this.id = id;
this.last_name = last_name;
this.email = email;
this.gender = gender;
this.department = department;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
public Employee(Integer id, String last_name, String email, String gender) {
super();
this.id = id;
this.last_name = last_name;
this.email = email;
this.gender = gender;
}
public Employee(){
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLast_name() {
return last_name;
}
public void setLast_name(String last_name) {
this.last_name = last_name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Override
public String toString() {
return "Employee [id=" + id + ", last_name=" + last_name + ", email=" + email + ", gender=" + gender + "]";
}
}
接口 EmployeeMapperDynamicSQL
public interface EmployeeMapperDynamicSQL {
//查询员工，要求，携带了哪个字段查询条件就带上这个字段的值
public List getEmpsByConditionIf(Employee employee);
public List getEmpsByConditionTrim(Employee employee);
public List getEmpsByConditionChoose(Employee employee);
public void updateEmp(Employee employee);
public List getEmpsByConditionForeach(@Param("ids")List ids);
public void addEmps(@Param("emps")List emps);
}
EmployeeMapperDynamicSQL.xml
<mapper namespace="com.mybatis.dao.EmployeeMapperDynamicSQL">
<select id="getEmpsByConditionIf" resultType="com.mybatis.bean.Employee">
select * from tbl_employee
<where>
<if test="id!=null">
and id = #{id}
if>
<if test="last_name!=null and last_name !=''">
and last_name like #{last_name}
if>
<if test="email!=null and email.trim()!=''">
and email = #{email}
if>
<if test="gender==0 or gender==1">
and gender = #{gender}
if>
where>
select>
<select id="getEmpsByConditionTrim" resultType="com.mybatis.bean.Employee">
select * from tbl_employee
<trim prefix="where" suffixOverrides="and">
<if test="id!=null">
id = #{id} and
if>
<if test="last_name!=null and last_name !=''">
last_name like #{last_name} and
if>
<if test="email!=null and email.trim()!=''">
email = #{email} and
if>
<if test="gender==0 or gender==1">
gender = #{gender}
if>
trim>
select>
<select id="getEmpsByConditionChoose" resultType="com.mybatis.bean.Employee">
select * from tbl_employee
<where>
<choose>
<when test="id!=null">
id=#{id}
when>
<when test="last_name!=null">
last_name like #{last_name}
when>
<when test="email!=null">
email = #{email}
when>
<otherwise>
gender = 0
otherwise>
choose>
where>
select>
<update id="updateEmp">
update tbl_employee
<set>
<if test="last_name!=null">
last_name=#{last_name},
if>
<if test="email!=null">
email=#{email},
if>
<if test="gender!=null">
gender=#{gender}
if>
set>
where id=#{id}
update>
<select id="getEmpsByConditionForeach" resultType="com.mybatis.bean.Employee">
select * from tbl_employee
<foreach collection="ids" item="item_id" separator=","
open="where id in(" close=")">
#{item_id}
foreach>
select>
<insert id="addEmps">
insert into tbl_employee(last_name,email,gender,d_id)
values
<foreach collection="emps" item="emp" separator=",">
(#{emp.last_name},#{emp.email},#{emp.gender},#{emp.department.id})
foreach>
insert>
mapper>测试类
public class MybatisTest {
public SqlSessionFactory getSqlSessionFactory() throws IOException {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
return new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void testDynamicSQL() throws IOException{
SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
SqlSession openSession = sqlSessionFactory.openSession();
try {
EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
Employee employee = new Employee(3,"Admin",null,null);
/*List emps = mapper.getEmpsByConditionIf(employee);
for (Employee employee2 : emps) {
System.out.println(employee2);
}*/
//测试 Trim
/*List emps2 = mapper.getEmpsByConditionTrim(employee);
for (Employee employee2 : emps2) {
System.out.println(employee2);
}*/
//测试Choose
/*List emps3 = mapper.getEmpsByConditionChoose(employee);
for (Employee employee2 : emps3) {
System.out.println(employee2);
}*/
//测试 set 更新
/*mapper.updateEmp(employee);
openSession.commit();*/
/*List emp2 = mapper.getEmpsByConditionForeach(Arrays.asList(1,2,3,4));
for (Employee employee2 : emp2) {
System.out.println(employee2);
}*/
} finally {
openSession.close();
}
}
@Test
public void testBatchSave() throws IOException{
SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
SqlSession openSession = sqlSessionFactory.openSession();
try {
EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
List emps = new ArrayList();
emps.add(new Employee(null, "smith", "[email protected]", "1",new Department(1)));
emps.add(new Employee(null, "alien", "[email protected]", "0",new Department(2)));
emps.add(new Employee(null, "TTT", "[email protected]", "1",new Department(1)));
emps.add(new Employee(null, "hhh", "[email protected]", "1",new Department(1)));
mapper.addEmps(emps);
openSession.commit();
}finally {
openSession.close();
}
}
}