我编辑阿贡Sagita的答案从子查询加入。 我不确定这两种方式有多大区别，但只是作为另一个参考。

SELECT  hostid, T2.VALUE AS A, T3.VALUE AS B, T4.VALUE AS C
FROM TableTest AS T1
LEFT JOIN TableTest T2 ON T2.hostid=T1.hostid AND T2.ITEMNAME='A'
LEFT JOIN TableTest T3 ON T3.hostid=T1.hostid AND T3.ITEMNAME='B'
LEFT JOIN TableTest T4 ON T4.hostid=T1.hostid AND T4.ITEMNAME='C'

我编辑阿贡Sagita的答案从子查询加入。 我不确定这两种方式有多大区别，但只是作为另一个参考。

SELECT  hostid, T2.VALUE AS A, T3.VALUE AS B, T4.VALUE AS C
FROM TableTest AS T1
LEFT JOIN TableTest T2 ON T2.hostid=T1.hostid AND T2.ITEMNAME='A'
LEFT JOIN TableTest T3 ON T3.hostid=T1.hostid AND T3.ITEMNAME='B'
LEFT JOIN TableTest T4 ON T4.hostid=T1.hostid AND T4.ITEMNAME='C'

我很抱歉这么说，也许我没有完全解决你的问题，但PostgreSQL比MySQL早10年，与MySQL相比是非常先进的，有很多方法可以轻松实现这一点。安装PostgreSQL并执行此查询

CREATE EXTENSION tablefunc;

然后瞧!这里有大量的文档:PostgreSQL: documentation: 9.1: tablefunc或this查询

CREATE EXTENSION hstore;

然后，瞧!PostgreSQL: Documentation: 9.0: hstore

我找到了一种方法，使用简单的查询使我的报告几乎动态地将行转换为列。你可以在这里在线查看和测试。

查询的列数是固定的，但值是动态的，并且基于行值。所以，我使用一个查询来构建表头，另一个查询来查看值:

SELECT distinct concat('<th>',itemname,'</th>') as column_name_table_header FROM history order by 1;

SELECT
     hostid
    ,(case when itemname = (select distinct itemname from history a order by 1 limit 0,1) then itemvalue else '' end) as col1
    ,(case when itemname = (select distinct itemname from history a order by 1 limit 1,1) then itemvalue else '' end) as col2
    ,(case when itemname = (select distinct itemname from history a order by 1 limit 2,1) then itemvalue else '' end) as col3
    ,(case when itemname = (select distinct itemname from history a order by 1 limit 3,1) then itemvalue else '' end) as col4
FROM history order by 1;

你也可以总结一下:

SELECT
     hostid
    ,sum(case when itemname = (select distinct itemname from history a order by 1 limit 0,1) then itemvalue end) as A
    ,sum(case when itemname = (select distinct itemname from history a order by 1 limit 1,1) then itemvalue end) as B
    ,sum(case when itemname = (select distinct itemname from history a order by 1 limit 2,1) then itemvalue end) as C
FROM history group by hostid order by 1;
+--------+------+------+------+
| hostid | A    | B    | C    |
+--------+------+------+------+
|      1 |   10 |    3 | NULL |
|      2 |    9 | NULL |   40 |
+--------+------+------+------+

RexTester测试结果:

http://rextester.com/ZSWKS28923

作为一个实际使用的例子，下面的报告以列的形式显示了船只/公共汽车出发和到达的时间，并有一个可视化的时间表。你会看到一个额外的列没有使用在最后一个col而不会混淆可视化: **票务系统的在线售票和存在

这不是你正在寻找的确切答案，但这是一个解决方案，我需要在我的项目，希望这有助于某人。这将列出用逗号分隔的1到n行项目。Group_Concat使这在MySQL中成为可能。

select
cemetery.cemetery_id as "Cemetery_ID",
GROUP_CONCAT(distinct(names.name)) as "Cemetery_Name",
cemetery.latitude as Latitude,
cemetery.longitude as Longitude,
c.Contact_Info,
d.Direction_Type,
d.Directions

    from cemetery
    left join cemetery_names on cemetery.cemetery_id = cemetery_names.cemetery_id 
    left join names on cemetery_names.name_id = names.name_id 
    left join cemetery_contact on cemetery.cemetery_id = cemetery_contact.cemetery_id 

    left join 
    (
        select 
            cemetery_contact.cemetery_id as cID,
            group_concat(contacts.name, char(32), phone.number) as Contact_Info

                from cemetery_contact
                left join contacts on cemetery_contact.contact_id = contacts.contact_id 
                left join phone on cemetery_contact.contact_id = phone.contact_id 

            group by cID
    )
    as c on c.cID = cemetery.cemetery_id


    left join
    (
        select 
            cemetery_id as dID, 
            group_concat(direction_type.direction_type) as Direction_Type,
            group_concat(directions.value , char(13), char(9)) as Directions

                from directions
                left join direction_type on directions.type = direction_type.direction_type_id

            group by dID


    )
    as d on d.dID  = cemetery.cemetery_id

group by Cemetery_ID

这个墓地有两个公共名称，因此名称被列在不同的行中，由一个id连接，但有两个名称id，查询产生如下内容 CemeteryID Cemetery_Name              纬度 1                    阿普尔顿,Sulpher弹簧35.4276242832293

我的解决方案:

select h.hostid, sum(ifnull(h.A,0)) as A, sum(ifnull(h.B,0)) as B, sum(ifnull(h.C,0)) as  C from (
select
hostid,
case when itemName = 'A' then itemvalue end as A,
case when itemName = 'B' then itemvalue end as B,
case when itemName = 'C' then itemvalue end as C
  from history 
) h group by hostid

它在提交的案例中产生预期的结果。