mybatis学习

Posted 2021-11-28 socketqiang

1.mybatis是一个ORM持久层框架的佼佼者，真正上实现了SQL语句与java代码分离。优秀的功能，动态分离，缓存，插件-pageHelper等

2.SQL语句使用in的时候，可以用数组封装in中的值。

3.批量操作数据的情况，可以把操作的数据封装在数组中

4.mybaits的入参处理：1.传递单个参数的形式（mybaits会自动进行参数的赋值） 2.传递多参数的时候（mybatis会自动封装在Map集合中）

3.Collection,List,Array作为参数，封装为Map，有一定规则的。

5.多参数传值的时候 #{名称}的名称是有规范的为[arg0,arg1,parm1,parm2] ，如果用#{username} and #{userpass} 会报错，用#{arg0} and #{arg1} 就不会报错。

可以用javabean处理：

代码如下：

public Person getPersonByNameAndGender(Person person)

可以用Map传递多参数:

代码如下：

public Person getPersonByNameAndGender(Map<String,Object> param);

利用注解@parm:

代码如下：

public Person getPersonByNameAndGender(@Param("username") String username,@Param("gender") String gender)

collection集合处理参数：

也可以用别名来代替key值：

  public Person getPersonByCollection(@Param("test") int[] ids);

动态遍历foreach;

利用<trim>标签

 <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        ID,
      </if>
      <if test="regType != null" >
        regType,
      </if>
      <if test="lastLandIp != null" >
        lastLandIp,
      </if>
      <if test="pwd != null" >
        PWD,
      </if>
      <if test="userName != null" >
        USERNAME,
      </if>
      <if test="email != null" >
        EMAIL,
      </if>
      <if test="isActivation != null" >
        ISACTIVATION,
      </if>
      <if test="emailActiveDate != null" >
        EMAILACTIVEDATE,
      </if>
      <if test="mobilePhone != null" >
        MOBILEPHONE,
      </if>
      <if test="isBindPhone != null" >
        ISBINDPHONE,
      </if>
      <if test="bindPhoneDate != null" >
        BINDPHONEDATE,
      </if>
      <if test="nickName != null" >
        NICKNAME,
      </if>
      <if test="male != null" >
        MALE,
      </if>
      <if test="birth != null" >
        BIRTH,
      </if>
      <if test="identityCode != null" >
        IDENTITYCODE,
      </if>
      <if test="identityType != null" >
        IDENTITYTYPE,
      </if>
      <if test="province != null" >
        PROVINCE,
      </if>
      <if test="city != null" >
        CITY,
      </if>
      <if test="address != null" >
        ADDRESS,
      </if>
      <if test="postCode != null" >
        POSTCODE,
      </if>
      <if test="homePhone != null" >
        HOMEPHONE,
      </if>
      <if test="regTime != null" >
        REGTIME,
      </if>
      <if test="lastLandTime != null" >
        LASTLANDTIME,
      </if>
      <if test="tempLastTime != null" >
        TEMPLASTTIME,
      </if>
      <if test="status != null" >
        STATUS,
      </if>
      <if test="payPwd != null" >
        PAYPWD,
      </if>
        ZM_SITEID,
      <if test="addDate != null" >
        ADDDATE,
      </if>
      <if test="realName != null" >
        REALNAME,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        #{id,jdbcType=DECIMAL},
      </if>
      <if test="regType != null" >
        #{regType,jdbcType=DECIMAL},
      </if>
      <if test="lastLandIp != null" >
        #{lastLandIp,jdbcType=VARCHAR},
      </if>
      <if test="pwd != null" >
        #{pwd,jdbcType=VARCHAR},
      </if>
      <if test="userName != null" >
        #{userName,jdbcType=VARCHAR},
      </if>
      <if test="email != null" >
        #{email,jdbcType=VARCHAR},
      </if>
      <if test="isActivation != null" >
        #{isActivation,jdbcType=DECIMAL},
      </if>
      <if test="emailActiveDate != null" >
        #{emailActiveDate,jdbcType=TIMESTAMP},
      </if>
      <if test="mobilePhone != null" >
        #{mobilePhone,jdbcType=VARCHAR},
      </if>
      <if test="isBindPhone != null" >
        #{isBindPhone,jdbcType=DECIMAL},
      </if>
      <if test="bindPhoneDate != null" >
        #{bindPhoneDate,jdbcType=TIMESTAMP},
      </if>
      <if test="nickName != null" >
        #{nickName,jdbcType=VARCHAR},
      </if>
      <if test="male != null" >
        #{male,jdbcType=DECIMAL},
      </if>
      <if test="birth != null" >
        #{birth,jdbcType=TIMESTAMP},
      </if>
      <if test="identityCode != null" >
        #{identityCode,jdbcType=VARCHAR},
      </if>
      <if test="identityType != null" >
        #{identityType,jdbcType=DECIMAL},
      </if>
      <if test="province != null" >
        #{province,jdbcType=VARCHAR},
      </if>
      <if test="city != null" >
        #{city,jdbcType=VARCHAR},
      </if>
      <if test="address != null" >
        #{address,jdbcType=VARCHAR},
      </if>
      <if test="postCode != null" >
        #{postCode,jdbcType=VARCHAR},
      </if>
      <if test="homePhone != null" >
        #{homePhone,jdbcType=VARCHAR},
      </if>
      <if test="regTime != null" >
        #{regTime,jdbcType=TIMESTAMP},
      </if>
      <if test="lastLandTime != null" >
        #{lastLandTime,jdbcType=TIMESTAMP},
      </if>
      <if test="tempLastTime != null" >
        #{tempLastTime,jdbcType=TIMESTAMP},
      </if>
      <if test="status != null" >
        #{status,jdbcType=DECIMAL},
      </if>
      <if test="payPwd != null" >
        #{payPwd,jdbcType=VARCHAR},
      </if>
       1,
      <if test="addDate != null" >
        #{addDate,jdbcType=TIMESTAMP},
      </if>
      <if test="realName != null" >
        #{realName,jdbcType=VARCHAR},
      </if>
    </trim>