Question

oracle中的表中应该存在两条记录，一条来自请求，另一条来自响应。

我想从今天开始选择所有这些记录，但问题是前两天或更长时间内可能存在另一对。如何确保将返回的记录仅为1，并且在前几天不存在

select A.referenceNum, A.datetime, A.Type from table A where A.datetime >= sysdate - 1

要想象，我想只选择参考号789ef 。

ReferenceNum DateTime类型

123ab（datetoday）请

123ab（datetoday）响应

456cd（datetoday）请

456cd（datetoday-2）响应

789ef（datetoday）请

Answer 1

您可以使用分析函数在单个表扫描中（与使用NOT EXISTS使用两个表扫描相比）进行此操作： SQL Fiddle

Oracle 11g R2架构设置：

CREATE TABLE table_name ( ReferenceNum,  DateTime,  Type ) AS
SELECT '123ab', SYSDATE, 'Request' FROM DUAL UNION ALL
SELECT '123ab', SYSDATE, 'Response' FROM DUAL UNION ALL
SELECT '456cd', SYSDATE, 'Request' FROM DUAL UNION ALL
SELECT '456cd', SYSDATE - 2, 'Response' FROM DUAL UNION ALL
SELECT '789ef', SYSDATE, 'Request' FROM DUAL;

查询1 ：

SELECT ReferenceNum
FROM   ( 
  SELECT ReferenceNum,
         COUNT( CASE WHEN TRUNC( DateTime ) =  TRUNC( SYSDATE ) THEN 1 END )
           OVER ( PARTITION BY ReferenceNum ) AS num_today,
         COUNT( CASE WHEN TRUNC( DateTime ) <> TRUNC( SYSDATE ) THEN 1 END )
           OVER ( PARTITION BY ReferenceNum ) AS num_other_day
  FROM   table_name t
)
WHERE  num_today = 1
AND    num_other_day = 0

<强> Results ：

| REFERENCENUM |
|--------------|
|        789ef |

Answer 2

使用NOT EXISTS运算符

SELECT A.referenceNum, A.datetime, A.Type 
from table A 
   where A.datetime >= sysdate - 1
  AND NOT EXISTS (
     SELECT null FROM table B
     WHERE A.referenceNum = B.referenceNum
       AND b.datetime < a.datetime
  )

Answer 3

SELECT referenceNum
FROM A A1
WHERE TRUNC(A1.datetime) > TRUNC(sysdate)-1
AND A1.Type              = 'Request'
AND NOT EXISTS
  (SELECT 1
  FROM A
  WHERE TRUNC(A.datetime) >= TRUNC(sysdate)-1
  AND A.Type               = 'Response'
  AND A.referenceNum       = A1.referenceNum
  )

oracle今天选择记录，但不包括前几天可能存在的记录

3 个答案: