Question

我有一张包含以下数据的表格

  <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>3.0.0</version>
            <executions>
                <execution>
                    <id>assemble-all</id>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                    <configuration>
                        <!--<finalName>PROJECT_NAME-${project.version}-shaded</finalName>-->
                        <relocations>
                            <relocation>
                                <pattern>com.google.common</pattern>
                                <shadedPattern>shaded.com.google.common</shadedPattern>
                            </relocation>
                            <relocation>
                                <pattern>com.google.protobuf</pattern>
                                <shadedPattern>shaded.com.google.protobuf</shadedPattern>
                            </relocation>
                        </relocations>
                        <artifactSet>
                            <includes>
                                <include>*:*</include>
                            </includes>
                        </artifactSet>
                    </configuration>
                </execution>
            </executions>
        </plugin>

现在我要选择村庄的最长日期

VC是疫苗的缩写形式

我想要的outPut是（最后一次接种疫苗的村庄日期）

villageId    ChildID   VC1_date   VC2_date   VC3_date   VC4_date   VC5_date
----------------------------------------------------------------------------
1             1         2/2/2015   2/4/2017   2/8/2013   2/2/2013   2/8/2011
1             2         2/3/2017   2/6/2013   2/3/2015   2/5/2014   2/4/2012
1             3         2/5/2013   2/8/2011   2/1/2017   2/8/2016   2/2/2011
2             1         2/6/2011   2/2/2014   2/2/2012   2/9/2018   2/6/2014
2             2         2/2/2013   2/4/2017   2/7/2011   2/4/2012   2/8/2016
2             3         2/1/2015   2/7/2018   2/9/2014   2/5/2011   2/1/2011

希望你明白我想要的......

Answer 1

我就是这样做的：

declare @vaccines table  
(villageId int,   
ChildID int,
VC1_date date,  
VC2_date date,  
VC3_date date,  
VC4_date date,  
VC5_date date)

INSERT INTO @vaccines VALUES(1, 1, '2015-02-02', '2017-04-02', '2013-08-02', '2013-02-02', '2011-08-02')
INSERT INTO @vaccines VALUES(1, 2, '2017-03-02', '2013-06-02', '2015-03-02', '2014-05-02', '2012-04-02')
INSERT INTO @vaccines VALUES(1, 3, '2013-05-02', '2011-08-02', '2017-01-02', '2016-08-02', '2011-02-02')
INSERT INTO @vaccines VALUES(2, 1, '2011-06-02', '2014-02-02', '2012-02-02', '2018-09-02', '2014-06-02')
INSERT INTO @vaccines VALUES(2, 2, '2013-02-02', '2017-04-02', '2011-07-02', '2012-04-02', '2016-08-02')
INSERT INTO @vaccines VALUES(2, 3, '2015-01-02', '2018-07-02', '2014-09-02', '2011-05-02', '2011-01-02')

SELECT villageId, MAX(vcdate) FROM
(SELECT villageId, ChildID, VC1_date as vcdate from @vaccines 
UNION
SELECT villageId, ChildID, VC2_date as vcdate from @vaccines 
UNION
SELECT villageId, ChildID, VC3_date as vcdate from @vaccines 
UNION
SELECT villageId, ChildID, VC4_date as vcdate from @vaccines 
UNION
SELECT villageId, ChildID, VC5_date as vcdate from @vaccines) g
GROUP BY villageId

SQL SELECT仅限具有最大日期的列

1 个答案: