3.MyBatis常用

1.数据库日期转格式

DATE_FORMAT(measuring_time, '%Y-%m-%d') AS measuring_time,

2.日期大于小于

<if test="beginDate != null and beginDate != ''">
  AND DATE_FORMAT(measuring_time, '%Y-%m-%d') >= #{beginDate}
</if>
<if test="endDate != null and endDate != ''">
  AND DATE_FORMAT(measuring_time, '%Y-%m-%d') <= #{endDate}
</if>


转义字符串：

<if test="startTime != null and startTime != ''">
   AND u.create_time >= #{startTime}
</if>
<if test="endTime != null and endTime != ''">
   AND u.create_time <= #{endTime}

3.foreach写法

<if test="healthStatuses != null">
  AND ha.health_status IN
  <foreach collection="healthStatuses" item="item" index="index" open="(" close=")" separator=",">
    #{item}
  </foreach>
</if>

4.模糊搜索

<if test="teamName != null and teamName != '' ">
  AND team_name LIKE CONCAT('%', #{teamName} ,'%')
</if>

5.case when

简单Case函数
CASE sex
WHEN '1' THEN '男'
WHEN '2' THEN '女'
ELSE '其他' END
 
--Case搜索函数 
CASE WHEN sex = '1' THEN '男' 
WHEN sex = '2' THEN '女' 
ELSE '其他' END  

6.find_in_set

<if test="chargeItemName != null and chargeItemName != ''">
    and find_in_set(charge_item_name,#{chargeItemName})
</if>

charge_item_name
#{chargeItemName}
用逗号拼接的放在后面
字符串没有逗号的放在前面

　　

1 获取数据库中的有数据的日期

SELECT

DISTINCT DATE_FORMAT(create_time, '%Y-%m-%d')

FROM

t_health

GROUP BY

create_time

ORDER BY

create_time DESC

LIMIT 50