使用条件聚合。 GROUP_CONCAT 如果特定字段名有多个匹配项，则可以使用返回逗号分隔的列表。

SELECT
    ID,
    GROUP_CONCAT(CASE WHEN FieldName = 'event_name' THEN FieldValue END) AS Title,
    GROUP_CONCAT(CASE WHEN FieldName = 'event_cost' THEN FieldValue END) AS Cost,
    GROUP_CONCAT(CASE WHEN FieldName = 'event_loc'  THEN FieldValue END) AS Location
FROM yourdata
GROUP BY ID

尝试此查询：

SELECT event_name AS 'Title', event_cost AS 'Cost', event_loc AS 'Location' 
FROM yourTableName

使用案例

select id, max( case when FieldName='event_name' then FieldValue end) as Title,
max(case when FieldName='event_cost' then FieldValue end) as cost,
max(case when FieldName='event_loc' then FieldValue end) as Location from t
group by id

https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=940326493ef7b561375953f85f65a4ea

id  Title   cost    Location
1   Event Title     10.0    Leeds
2   Another Event   15.0    London

您可以执行条件聚合：

select max(case when FieldName = 'event_name' then FieldValue end) as Title,
       max(case when FieldName = 'event_cost ' then FieldValue end) as Cost,
       max(case when FieldName = 'event_loc' then FieldValue end) as Location
from table t
group by id;

用例和聚合：

select max(case when fieldname='event_name' then FieldValue) as title,
max(case when fieldname='event_cost' then FieldValue) as cost,
max(case when fieldname='event_loc' then FieldValue) as location,
from tablename group by id