Question

我正在撰写一个查询，并希望将结果放在一列中我目前的结果会像这样返回

    <?xml version="1.0" encoding="UTF-8"?>

    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:tx="http://www.springframework.org/schema/tx" 
           xmlns:aop="http://www.springframework.org/schema/aop"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd
           http://www.springframework.org/schema/tx
           http://www.springframework.org/schema/tx/spring-tx-2.0.xsd
           http://www.springframework.org/schema/aop
           http://www.springframework.org/schema/aop/spring-aop-2.0.xsd">

      <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/>  
      <bean id = "RcMaintenanceService" class="com.rh.services.RcAbcMaintenanceServiceImpl" autowire="byName" />

    <aop:config>
            <aop:pointcut id="rOperation" expression="execution(* com.rh.services.*.*(..))"/>
            <aop:advisor advice-ref="txAdvice" pointcut-ref="rOperation"/>
        </aop:config>

    <tx:advice id="txAdvice" transaction-manager="transactionManager">
            <tx:attributes>
                   <tx:method name="*"/>
            </tx:attributes>
        </tx:advice>

    <bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
            <property name="jndiName" value="java:comp/env/jdbc/db1" />
        </bean> 
        <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
            <property name="entityManagerFactory" ref="entityManagerFactory"/>
            <property name="dataSource" ref="dataSource"/>
        </bean>

        <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
               <property name="persistenceUnitName" value="db1" />     
            <property name="dataSource" ref="dataSource"/>
            <property name="jpaVendorAdapter">
                <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> 
                    <property name="showSql" value="true"/>
                    <property name="generateDdl" value="false"/>
                    <property name="database" value="MYSQL" />
                    <property name="databasePlatform" value="org.hibernate.dialect.MySQL5Dialect"/>
                </bean>
            </property>
            <property name="jpaDialect">
                <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect">
                </bean>
            </property>
        </bean>

我希望结果像这样返回

Column1     Column2    column3
1              A         CAT

Answer 1

SELECT Column1 FROM TableName
UNION ALL
SELECT Column2 FROM TableName
UNION ALL
SELECT Column3 FROM TableName

如果您不想要重复值，请使用UNION代替UNION ALL。

您也可以使用UNPIVOT运算符

执行此操作

SELECT Column123
FROM
(
  SELECT Column1, Column2, Column3 
  FROM TableName
) AS tmp
UNPIVOT 
(
  Column123 FOR ColumnAll IN (Column1, Column2, Column3)
) AS unpvt;

https://www.w3schools.com/sql/sql_union.asp
https://www.mssqltips.com/sqlservertip/3000/use-sql-servers-unpivot-operator-to-help-normalize-output/

Answer 2

答案是......这取决于......

如果列数未知..则使用UZI建议的

的unpivot

如果您知道所有列并且是一个小的有限集...

你可以直接去

Select
column1
from table

union all
select column2
from table

union all
select column3
from table

Answer 3

T表的笛卡尔乘积，派生表为3行。（#t的每一行显示3次，а= 1，а= 2，а= 3）。对于第一种情况，我们从Column1获取值，而对于第二个 - 来自Column2和来自Column3。在这里，肯定有联合和加入，但在我看来，标题的问题意味着单一扫描表。

CREATE TABLE #t (Column1 NVARCHAR(25),Column2 NVARCHAR(25), column3 NVARCHAR(25))

INSERT INTO #t
SELECT '1','A','CAT'

SELECT
CASE a WHEN 1 THEN Column1  WHEN 2 THEN Column2 ELSE column3 END col
FROM #t, (SELECT 1 a UNION ALL SELECT 2 UNION ALL SELECT 3) B

DROP TABLE #t

如何将多列组合成一列？

3 个答案: