Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

GROUP BY to combine/concat a column [duplicate]

People also ask

Can we use concat in group by?

MySQL | Group_CONCAT() Function. The GROUP_CONCAT() function in MySQL is used to concatenate data from multiple rows into one field. This is an aggregate (GROUP BY) function which returns a String value, if the group contains at least one non-NULL value. Otherwise, it returns NULL.

How do you concatenate rows by grouping data by column?

In the Advanced Combine Rows window, choose the column which you want to combine rows based on, and click Primary Key to set it as key column. 3. Select the column you need to combine, click Combine, and choose one delimiter you use to separate the combined contents.

How do you concatenate a column from multiple rows into a single column?

You can concatenate rows into single string using COALESCE method. This COALESCE method can be used in SQL Server version 2008 and higher. All you have to do is, declare a varchar variable and inside the coalesce, concat the variable with comma and the column, then assign the COALESCE to the variable.


SELECT
     [User], Activity,
     STUFF(
         (SELECT DISTINCT ',' + PageURL
          FROM TableName
          WHERE [User] = a.[User] AND Activity = a.Activity
          FOR XML PATH (''))
          , 1, 1, '')  AS URLList
FROM TableName AS a
GROUP BY [User], Activity
  • SQLFiddle Demo

A good question. Should tell you it took some time to crack this one. Here is my result.

DECLARE @TABLE TABLE
(  
ID INT,  
USERS VARCHAR(10),  
ACTIVITY VARCHAR(10),  
PAGEURL VARCHAR(10)  
)

INSERT INTO @TABLE  
VALUES  (1, 'Me', 'act1', 'ab'),
        (2, 'Me', 'act1', 'cd'),
        (3, 'You', 'act2', 'xy'),
        (4, 'You', 'act2', 'st')


SELECT T1.USERS, T1.ACTIVITY,   
        STUFF(  
        (  
        SELECT ',' + T2.PAGEURL  
        FROM @TABLE T2  
        WHERE T1.USERS = T2.USERS  
        FOR XML PATH ('')  
        ),1,1,'')  
FROM @TABLE T1  
GROUP BY T1.USERS, T1.ACTIVITY