当我执行以下查询时,我得到的消息就像
“Ora-01427单行子查询返回多行”
SELECT E.I_EmpID AS EMPID,
E.I_EMPCODE AS EMPCODE,
E.I_EmpName AS EMPNAME,
REPLACE(TO_CHAR(A.I_REQDATE, 'DD-Mon-YYYY'), ' ', '') AS FROMDATE,
REPLACE(TO_CHAR(A.I_ENDDATE, 'DD-Mon-YYYY'), ' ', '') AS TODATE,
TO_CHAR(NOD) AS NOD,
DECODE(A.I_DURATION,
'FD',
'FullDay',
'FN',
'ForeNoon',
'AN',
'AfterNoon') AS DURATION,
L.I_LeaveType AS LEAVETYPE,
REPLACE(TO_CHAR((SELECT C.I_WORKDATE
FROM T_COMPENSATION C
WHERE C.I_COMPENSATEDDATE = A.I_REQDATE
AND C.I_EMPID = A.I_EMPID),
'DD-Mon-YYYY'),
' ',
'') AS WORKDATE,
A.I_REASON AS REASON,
AP.I_REJECTREASON AS REJECTREASON
FROM T_LEAVEAPPLY A
INNER JOIN T_EMPLOYEE_MS E
ON A.I_EMPID = E.I_EmpID
AND UPPER(E.I_IsActive) = 'YES'
AND A.I_STATUS = '1'
INNER JOIN T_LeaveType_MS L
ON A.I_LEAVETYPEID = L.I_LEAVETYPEID
LEFT OUTER JOIN T_APPROVAL AP
ON A.I_REQDATE = AP.I_REQDATE
AND A.I_EMPID = AP.I_EMPID
AND AP.I_APPROVALSTATUS = '1'
WHERE E.I_EMPID <> '22'
ORDER BY A.I_REQDATE DESC
当我执行此操作而没有ORDER BY A.I_REQDATE DESC时,它返回100行...
使用以下查询:
SELECT E.I_EmpID AS EMPID,
E.I_EMPCODE AS EMPCODE,
E.I_EmpName AS EMPNAME,
REPLACE(TO_CHAR(A.I_REQDATE, 'DD-Mon-YYYY'), ' ', '') AS FROMDATE,
REPLACE(TO_CHAR(A.I_ENDDATE, 'DD-Mon-YYYY'), ' ', '') AS TODATE,
TO_CHAR(NOD) AS NOD,
DECODE(A.I_DURATION,
'FD',
'FullDay',
'FN',
'ForeNoon',
'AN',
'AfterNoon') AS DURATION,
L.I_LeaveType AS LEAVETYPE,
REPLACE(TO_CHAR((SELECT max(C.I_WORKDATE)
FROM T_COMPENSATION C
WHERE C.I_COMPENSATEDDATE = A.I_REQDATE
AND C.I_EMPID = A.I_EMPID),
'DD-Mon-YYYY'),
' ',
'') AS WORKDATE,
A.I_REASON AS REASON,
AP.I_REJECTREASON AS REJECTREASON
FROM T_LEAVEAPPLY A
INNER JOIN T_EMPLOYEE_MS E
ON A.I_EMPID = E.I_EmpID
AND UPPER(E.I_IsActive) = 'YES'
AND A.I_STATUS = '1'
INNER JOIN T_LeaveType_MS L
ON A.I_LEAVETYPEID = L.I_LEAVETYPEID
LEFT OUTER JOIN T_APPROVAL AP
ON A.I_REQDATE = AP.I_REQDATE
AND A.I_EMPID = AP.I_EMPID
AND AP.I_APPROVALSTATUS = '1'
WHERE E.I_EMPID <> '22'
ORDER BY A.I_REQDATE DESC
诀窍是通过添加聚合函数强制内部查询只返回一条记录(我在这里使用了max())。就查询而言,这将完美地工作,但是,老实说,OP应该通过检查数据来调查内部查询返回多个记录的原因。这些多条记录真的与商业明智相关吗?
唯一的子查询似乎是这样 - 尝试将ROWNUM
限制添加到可确定的位置:
(SELECT C.I_WORKDATE
FROM T_COMPENSATION C
WHERE C.I_COMPENSATEDDATE = A.I_REQDATE AND ROWNUM <= 1
AND C.I_EMPID = A.I_EMPID)
你需要调查为什么这不是唯一的,但是 - 例如该员工可能在匹配日期有多个C.I_COMPENSATEDDATE
。
出于性能原因,您还应该查看查找子查询是否可以重新排列为内/左连接,即
SELECT
...
REPLACE(TO_CHAR(C.I_WORKDATE, 'DD-Mon-YYYY'),
' ',
'') AS WORKDATE,
...
INNER JOIN T_EMPLOYEE_MS E
...
LEFT OUTER JOIN T_COMPENSATION C
ON C.I_COMPENSATEDDATE = A.I_REQDATE
AND C.I_EMPID = A.I_EMPID
...