mybatis-参数别名

<delete id='del' parameterType='java.lang.Long'>
delete from student where s_id=#{id};
</delete>

int del(@Param("id")Long id);

一个删除的sql语句，他的参数是一个long类型的id，显然@param设置了这个参数别名为id。但是假如我们不使用别名还是否会成功呢？
我们去掉@param

int del(Long id);

执行后，我们发现并未报错。那我们将名称进行更改呢？

int del(Long idd);

<delete id='del' parameterType='java.lang.Long'>
delete from student where s_id=#{idds};
</delete>

还是运行成功了，但这种情况当我们的参数增加为2就不管用了，这说明这两者之间并不是强绑定的关系。如果我们没有规定他的参数别名他默认为param1，param2…。
那如果我们传输的是pojo呢？

package online.fatotaku.entities;

public class Student {
    private Long id;
    private String name;
    private Integer age;
    private Integer sex;
    private Integer gId;
    private Integer cId;
    private Grade grade;
    private Class rank;

    public Student() {
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex=" + sex +
                ", gId=" + gId +
                ", cId=" + cId +
                ", grade=" + grade +
                ", rank=" + rank +
                '}';
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Integer getSex() {
        return sex;
    }

    public void setSex(Integer sex) {
        this.sex = sex;
    }

    public Integer getgId() {
        return gId;
    }

    public void setgId(Integer gId) {
        this.gId = gId;
    }

    public Integer getcId() {
        return cId;
    }

    public void setcId(Integer cId) {
        this.cId = cId;
    }

    public Grade getGrade() {
        return grade;
    }

    public void setGrade(Grade grade) {
        this.grade = grade;
    }

    public Class getRank() {
        return rank;
    }

    public void setRank(Class rank) {
        this.rank = rank;
    }

    public Student(Long id, String name, Integer age, Integer sex, Integer gId, Integer cId, Grade grade, Class rank) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.gId = gId;
        this.cId = cId;
        this.grade = grade;
        this.rank = rank;
    }

    public Student(Long id, String name, Integer age, Integer sex, Grade grade, Class rank) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.grade = grade;
        this.rank = rank;
    }

    public Student(Long id, String name, Integer age, Integer sex, Integer gId, Integer cId) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.gId = gId;
        this.cId = cId;
    }
}

    int add(Student student);

    <insert id="add"  parameterType="student">
        insert into student values (#{id},#{name},#{age},#{sex},#{gId},#{cId});
    </insert>

执行成功，新版mybatis在设置中已经默认打开别名映射，所以如果是对象，可以直接使用属性名，但如果是普通的一个个参数，这里推荐写上@param来规定别名。