//携带了哪个字段查询条件就带上这个字段的值
public List<Employee> getEmpsByConditionIf(Employee employee);
<!-- 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<Employee> getEmpsByConditionIf(Employee employee); -->
<select id="getEmpsByConditionIf" resultType="com.atguigu.mybatis.bean.Employee">
select * from tbl_employee
<!-- where -->
<where>
<!-- test：判断表达式（OGNL）
OGNL参照PPT或者官方文档。
c:if test
从参数中取值进行判断
遇见特殊符号应该去写转义字符：
&&：&&
-->
<if test="id!=null">
id=#{id}
</if>
<if test="lastName!=null && lastName!=""">
and last_name like #{lastName}
</if>
<if test="email!=null and email.trim()!=""">
and email=#{email}
</if>
<!-- ognl会进行字符串与数字的转换判断 "0"==0 -->
<if test="gender==0 or gender==1">
and gender=#{gender}
</if>
</where>
</select>
@Test
public void testDynamicSql() throws IOException{
SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
SqlSession openSession = sqlSessionFactory.openSession();
try{
EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
//select * from tbl_employee where id=? and last_name like ?
//测试if\where
Employee employee = new Employee(1, "Admin", null, null);
/* List<Employee> emps = mapper.getEmpsByConditionIf(employee );
for (Employee emp : emps) {
System.out.println(emp);
}*/
//查询的时候如果某些条件没带可能sql拼装会有问题
//1、给where后面加上1=1，以后的条件都and xxx.
//2、mybatis使用where标签来将所有的查询条件包括在内。mybatis就会将where标签中拼装的sql，多出来的and或者or去掉
//where只会去掉第一个多出来的and或者or。
package com.atguigu.mybatis.bean;
import org.apache.ibatis.type.Alias;
public class Employee {
private Integer id;
private String lastName;
private String email;
private String gender;
private Department dept;
public Employee() {
super();
}
public Employee(Integer id, String lastName, String email, String gender) {
super();
this.id = id;
this.lastName = lastName;
this.email = email;
this.gender = gender;
}
//get set
@Override
public String toString() {
return "Employee [id=" + id + ", lastName=" + lastName + ", email="
+ email + ", gender=" + gender + "]";
}
}
public Long addEmp(Employee employee);
<!-- public void addEmp(Employee employee); -->
<!-- parameterType：参数类型，可以省略，
获取自增主键的值：
mysql支持自增主键，自增主键值的获取，mybatis也是利用statement.getGenreatedKeys()；
useGeneratedKeys="true"；使用自增主键获取主键值策略
keyProperty；指定对应的主键属性，也就是mybatis获取到主键值以后，将这个值封装给javaBean的哪个属性
Employee emp = new Employee(....);
addEmp(emp);执行sql
System.out.println(emp.getId());就可以获取到自增的主键了
-->
<insert id="addEmp" parameterType="com.atguigu.mybatis.bean.Employee"
useGeneratedKeys="true" keyProperty="id" databaseId="mysql">
insert into tbl_employee(last_name,email,gender)
values(#{lastName},#{email},#{gender})
</insert>
/**
* 测试自增主键
* 1、mybatis允许增删改直接定义以下类型返回值
* Integer、Long、Boolean、void
* 2、我们需要手动提交数据
* sqlSessionFactory.openSession();===》手动提交
* sqlSessionFactory.openSession(true);===》自动提交
* @throws IOException
*/
@Test
public void test03() throws IOException{
SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
//1、获取到的SqlSession不会自动提交数据
SqlSession openSession = sqlSessionFactory.openSession();
try{
EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);
//测试添加
Employee employee = new Employee(null, "jerry4",null, "1");
mapper.addEmp(employee);
System.out.println(employee.getId());//获取到被添加数据的id
//2、手动提交数据
openSession.commit();
}finally{
openSession.close();
}
}