我必须根据第一列在同一 table 中连接两行

Question

这里我展示的是table

Column_1                                                Column_2
------------------------------------------------------------------------------
GERD                            Onset: 3 Days. Pain scale: 9/10. 
hyperlipidemia                  The diabetes started in 2004 and is controlled.
asthma                          Onset: 6 hours ago.  The initial visit date was 
headache                        Onset: 1 Day.  The severity of the problem is 
hyperlipidemia (comments)       This is a test Comment where i can try
asthma (comments)               Test Comment for the query

我要的是这个

Column_1                                                Column_2
    ------------------------------------------------------------------------------
    GERD                            Onset: 3 Days. Pain scale: 9/10.     
    hyperlipidemia                  The diabetes started in 2004 and is controlled. Comment :  This is a test Comment where i can try
    asthma                          Onset: 6 hours ago.  The initial visit date was 
    headache                        Onset: 1 Day.  The severity of the problem is. Comment : Test Comment for the query

我的SQL声明：

 select a.create_timestamp, a.Column_1 as Name, a.Column_2+b.Column_2 as DetailsAndComment from HOPI_ex_ a, HOPI_ex_ b
where a.Column_1+' (comments)' = b.Column_1

我只得到两行 Gerd 和高脂血症

Answer 1

您只得到两行的原因是您的 where 子句过滤掉了没有相应评论的行。我认为使用左连接应该做你想做的。请试试这个：

select 
    a.create_timestamp, 
    a.Column_1 as Name, 
    case when b.Column_2 is null then a.Column_2 else  a.Column_2 + ' Comment: ' + b.Column_2 end as DetailsAndComment 
from HOPI_ex_ a
left join HOPI_ex_ b on a.Column_1 + ' (comments)' = b.Column_1
where a.Column_1 not like '%(comments)%'

使用您的示例数据，上述查询的结果将是：

Name              DetailsAndComment
----------------- -----------------------------------------
GERD              Onset: 3 Days. Pain scale: 9/10.
hyperlipidemia    The diabetes started in 2004 and is controlled. Comment: This is a test Comment where i can try
asthma            Onset: 6 hours ago.  The initial visit date was Comment: Test Comment for the query
headache          Onset: 1 Day.  The severity of the problem is

我必须根据第一列在同一 table 中连接两行

I have to concatenate two rows in the same table based on the first columns

sql-server

sql-server-2008