记一次PageHelper分页查询出现的去重失效问题
背景
单表查询福利明细数据
一个人员的福利数据明细对应多个明细类别行
例如：
张三（项目一）：
社保：
个人缴纳： xxx
公司缴纳： xxx
公积金：
个人缴纳： xxx
公司缴纳： xxx
表结构示例如下：
| cPersonName | cProgramCode | cBoonCode | iPersonalPay | iCompanyPay |
|---|---|---|---|---|
| 张三 | 01 | 001（社保） | 300 | 600 |
| 张三 | 01 | 002（公积金） | 300 | 300 |
预期结果
| cPersonName | cProgramCode | 其他信息列 |
|---|---|---|
| 张三 | 01 |
实际结果
| cPersonName | cProgramCode | 其他信息列 |
|---|---|---|
| 张三 | 01 | xxx |
| 张三 | 01 | xxx |
Mapper如下
<select id="findBoonDetails" parameterType="cn.apcinfo.salary.query.boon.BoonListCondition" resultMap="boonMainMap">
SELECT
DISTINCT d.cDepCode as cDeptCode,d.cDepName as cDeptName,[iYear],
[iMonth],bd.cBoonProgram,wp.cprjname as cProgramName,cPayType as payType,
CASE cPayType WHEN 0 THEN '缴交' ELSE '补缴' END AS cPayType,bd.cPsnNum,p.cPsn_Name,
CASE iStatus WHEN 1 THEN '待处理' WHEN 2 THEN '已审核'
WHEN 3 THEN '已退回' ELSE '已撤销' END AS iStatus
FROM boon_data bd
JOIN ${ufname}..Department d ON bd.cDeptCode = d.cDepCode
JOIN ${ufname}..hr_wm_project wp ON bd.cBoonProgram = wp.cprjcode
JOIN ${ufname}..hr_hi_person p ON p.cPsn_Num = bd.cPsnNum
WHERE 1=1
ORDER BY [cDeptCode],[iYear],[iMonth],[cBoonProgram],[cPayType],[cPsnNum],[cBoonCode]
</select>
注意：以上SQL语句直接放到SQL查询分析器中报错如下：
但是使用PageHelper却不会报错，只会产生重复的数据行。
查看控制台打印的SQL语句如下：
-- 查询总数据条数SQL
SELECT count(0) FROM (
SELECT
DISTINCT d.cDepCode AS cDeptCode, d.cDepName AS cDeptName, [iYear], [iMonth], bd.cBoonProgram, wp.cprjname AS cProgramName, cPayType AS payType,
CASE cPayType WHEN 0 THEN '缴交' ELSE '补缴' END AS cPayType, bd.cPsnNum, p.cPsn_Name,
CASE iStatus WHEN 1 THEN '待处理' WHEN 2 THEN '已审核' WHEN 3 THEN '已退回' ELSE '已撤销' END AS iStatus
FROM boon_data bd JOIN UFDATA_800_2019..Department d
ON bd.cDeptCode = d.cDepCode
JOIN ${ufname}..hr_wm_project wp
ON bd.cBoonProgram = wp.cprjcode
JOIN ${ufname}..hr_hi_person p
ON p.cPsn_Num = bd.cPsnNum
WHERE 1 = 1 AND cBoonProgram = ? AND cPayType = ?
) table_count
-- 分页查询SQL
SELECT TOP 10 cDeptCode, cDeptName, [iYear], [iMonth], cBoonProgram, cProgramName, payType, cPayType, cPsnNum, cPsn_Name, iStatus FROM (
SELECT ROW_NUMBER() OVER (ORDER BY ROW_ALIAS_1, [iYear], [iMonth], ROW_ALIAS_2, ROW_ALIAS_3, ROW_ALIAS_4,ROW_ALIAS_5) PAGE_ROW_NUMBER, cDeptCode, cDeptName, [iYear], [iMonth], cBoonProgram, cProgramName, payType, cPayType, cPsnNum, cPsn_Name, iStatus FROM (
SELECT
DISTINCT d.cDepCode AS cDeptCode, d.cDepName AS cDeptName, [iYear], [iMonth],
bd.cBoonProgram, wp.cprjname AS cProgramName, cPayType AS payType,
CASE cPayType WHEN 0 THEN '缴交' ELSE '补缴' END AS cPayType, bd.cPsnNum, p.cPsn_Name, CASE iStatus WHEN 1 THEN '待处理' WHEN 2 THEN '已审核' WHEN 3 THEN '已退回' ELSE '已撤销' END AS iStatus,
[cDeptCode] AS ROW_ALIAS_1, [cBoonProgram] AS ROW_ALIAS_2, [cPayType] AS ROW_ALIAS_3, [cPsnNum] AS ROW_ALIAS_4
FROM boon_data bd JOIN UFDATA_800_2019..Department d
ON bd.cDeptCode = d.cDepCode JOIN UFDATA_800_2019..hr_wm_project wp
ON bd.cBoonProgram = wp.cprjcode JOIN UFDATA_800_2019..hr_hi_person p
ON p.cPsn_Num = bd.cPsnNum WHERE 1 = 1
AND cBoonProgram = ? AND cPayType = ?)
AS PAGE_TABLE_ALIAS)
AS PAGE_TABLE_ALIAS
WHERE PAGE_ROW_NUMBER > 0 ORDER BY PAGE_ROW_NUMBER
观察如上两条SQL语句不难发现：
-
查询数据条数的SQL中，PageHelper移除了Order By子句
-
分页查询数据的SQL中，PageHelper将Order By子句修改成了
ROW_NUMBER() OVER (ORDER BY ROW_ALIAS_1, [iYear], [iMonth], ROW_ALIAS_2, ROW_ALIAS_3, ROW_ALIAS_4)
问题就在这里，PageHelper直接将OrderBy子句中需要且结果字段中不存在（别名匹配的不算）的列拼接到了原SQL末尾
[cDeptCode] AS ROW_ALIAS_1, [cBoonProgram] AS ROW_ALIAS_2, [cPayType] AS ROW_ALIAS_3, [cPsnNum] AS ROW_ALIAS_4,[cBoonCode] AS ROW_ALIAS_5
但是我原本的结果中并没有cBoonCode字段，所以取到的结果集就表现成了去重失效。
总结：遇到这样的问题，还是要细心检查SQL语句（我是直接拷贝的另一条SQL，改了一下，结果排序字段忘记删了），查看控制台输出的SQL与原SQL语句有什么区别，将处理后的SQL和原SQL语句认真比对。