How to concatenate multiple rows inside a single row in SQL? [duplicate]

问题

This question already has answers here:

DB2 Comma Separated Output by Groups (7 answers)

Closed 6 years ago.

How do I concatenate multiple rows into a single row using SQL? My database is DB2

TableFoo
 -------
 Id      Name
 1       Apples
 1       Tomatoes
 1       Potatoes
 2       Banana
 2       Peach

I want something like

ID       FruitsAvailable
-------------------------
 1       Apples, Tomatoes, Potatoes

回答1:

try this

  SELECT id ,FruitsAvailable 
  FROM
      (SELECT id , group_concat(Name) as FruitsAvailable 
       FROM  TableFoo
       WHERE id = 1) t

HERE DEMO SQLFIDDLE

EDIT: in db2 you need to create function and then call it

 CREATE FUNCTION MySchema/MyUDF (
PARCol2 CHAR(5) )
RETURNS VARCHAR(1024)   
LANGUAGE SQL 
NOT DETERMINISTIC 
READS SQL DATA 
CALLED ON NULL INPUT 
DISALLOW PARALLEL 

 BEGIN 
  DECLARE ReturnVal VARCHAR(1024) NOT NULL DEFAULT '';

  FOR CsrC1 AS C1 CURSOR 
      FOR SELECT MyCol1 
             FROM MyTable 
             WHERE MyCol2 = ParCol2 
      DO SET ReturnVal = ReturnVal Concat CsrC1.MyCol1; 
  END FOR; 

  RETURN LTRIM(ReturnVal); 
 END  ; 

and then call it here

     Select  id, MyUDF(Name) as FruitsAvailable
     From TableFoo 
     where id = 1 

回答2:

Use this query:

SELECT Id, GROUP_CONCAT(Name SEPARATOR ', ') FROM TableFoo GROUP BY Id;

来源：https://stackoverflow.com/questions/14851025/how-to-concatenate-multiple-rows-inside-a-single-row-in-sql