问题

I have a table named TABLE for example looking like:

ID | email

--------------

1 | a@a.com

1 | b@b.com

2 | c@c.com

3 | d@d.com

3 | e@e.com

and I would like to return something like

ID | email1 | email2

--------------------

1 | a@a.com| b@b.com

2 | c@c.com|

3 | d@d.com| e@e.com

I was wondering how I could use pivoting to help me get rid of duplicate ID rows and just add an extra column for their other emails. Thanks for the help.

SELECT id, email1, email2, email3

FROM (

SELECT id,

email,

ROW_NUMBER() OVER (PARTITION BY id ORDER BY email) AS emailRank

FROM TABLE

)

pivot( max(email) FOR emailRank IN (1 as email1, 2 as email2, 3 as email3));

Edit: fixed above thanks to beach's answer

回答1:

I prefer using the GROUP BY solution with CASE expression.

SELECT

id,

MAX(CASE WHEN emailRank = 1 THEN email END) AS [1],

MAX(CASE WHEN emailRank = 2 THEN email END) AS [2],

MAX(CASE WHEN emailRank = 3 THEN email END) AS [3],

MAX(CASE WHEN emailRank = 4 THEN email END) AS [4]

FROM (

SELECT

id,

email,

ROW_NUMBER() OVER (PARTITION BY id ORDER BY email) AS emailRank

FROM TABLE

)

GROUP BY id;

Original Pivot example had type and missing ")". Try the following to get pivot working:

pivot( max(email) FOR emailRank IN (1,2,3));

回答2:

You can use a procedure or a combination of group by rownum and decode. Personally, I find the procedure approach cleaner.

See: http://asktom.oracle.com/pls/apex/f?p=100:11:0::NO::P11_QUESTION_ID:15151874723724

来源：https://stackoverflow.com/questions/6963684/oracle10g-sql-pivot