How to use GROUP BY to concatenate strings in SQL Server?
No CURSOR, WHILE loop, or User-Defined Function needed.
Just need to be creative with FOR XML and PATH.
[Note: This solution only works on SQL 2005 and later. Original question didn't specify the version in use.]
CREATE TABLE #YourTable ([ID] INT, [Name] CHAR(1), [Value] INT)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (1,'A',4)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (1,'B',8)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (2,'C',9)
SELECT
[ID],
STUFF((
SELECT ', ' + [Name] + ':' + CAST([Value] AS VARCHAR(MAX))
FROM #YourTable
WHERE (ID = Results.ID)
FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
,1,2,'') AS NameValues
FROM #YourTable Results
GROUP BY ID
DROP TABLE #YourTable
How to use GROUP BY to concatenate strings in MySQL?
SELECT id, GROUP_CONCAT(name SEPARATOR ' ') FROM table GROUP BY id;
https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_group-concat
From the link above, GROUP_CONCAT
: This function returns a string result with the concatenated non-NULL values from a group. It returns NULL if there are no non-NULL values.
Sql select group by and string concat
this will work with sql-server 2008
SELECT p1.ID,
( SELECT NAME + ' and '
FROM YourTable p2
WHERE p2.ID = p1.ID
ORDER BY NAME
FOR XML PATH('') ) AS Name,
sum(Amount)
FROM YourTable p1
GROUP BY ID ;
Concatenate many rows into a single text string with grouping
try this -
SELECT DISTINCT
fileid
, STUFF((
SELECT N', ' + CAST([filename] AS VARCHAR(255))
FROM tblFile f2
WHERE f1.fileid = f2.fileid ---- string with grouping by fileid
FOR XML PATH (''), TYPE), 1, 2, '') AS FileNameString
FROM tblFile f1
MS SQL - group by concat string
In sql server you can use FOR XML PATH
select SubscriberId,
categoriesAdded=Stuff((SELECT ',' + CAST(CategoryId as VARCHAR(255)) FROM catsToAdd t1 WHERE t1.SubscriberId=@categoriesToAdd.SubscriberId
FOR XML PATH (''))
, 1, 1, '' )
from @categoriesToAdd as catsToAdd
GROUP BY SubscriberId
How to concatenate strings of a string field in a PostgreSQL 'group by' query?
PostgreSQL 9.0 or later:
Modern Postgres (since 2010) has the string_agg(expression, delimiter)
function which will do exactly what the asker was looking for:
SELECT company_id, string_agg(employee, ', ')
FROM mytable
GROUP BY company_id;
Postgres 9 also added the ability to specify an ORDER BY
clause in any aggregate expression; otherwise you have to order all your results or deal with an undefined order. So you can now write:
SELECT company_id, string_agg(employee, ', ' ORDER BY employee)
FROM mytable
GROUP BY company_id;
PostgreSQL 8.4.x:
PostgreSQL 8.4 (in 2009) introduced the aggregate function array_agg(expression)
which collects the values in an array. Then array_to_string()
can be used to give the desired result:
SELECT company_id, array_to_string(array_agg(employee), ', ')
FROM mytable
GROUP BY company_id;
PostgreSQL 8.3.x and older:
When this question was originally posed, there was no built-in aggregate function to concatenate strings. The simplest custom implementation (suggested by Vajda Gabo in this mailing list post, among many others) is to use the built-in textcat
function (which lies behind the ||
operator):
CREATE AGGREGATE textcat_all(
basetype = text,
sfunc = textcat,
stype = text,
initcond = ''
);
Here is the CREATE AGGREGATE
documentation.
This simply glues all the strings together, with no separator. In order to get a ", " inserted in between them without having it at the end, you might want to make your own concatenation function and substitute it for the "textcat" above. Here is one I put together and tested on 8.3.12:
CREATE FUNCTION commacat(acc text, instr text) RETURNS text AS $$
BEGIN
IF acc IS NULL OR acc = '' THEN
RETURN instr;
ELSE
RETURN acc || ', ' || instr;
END IF;
END;
$$ LANGUAGE plpgsql;
This version will output a comma even if the value in the row is null or empty, so you get output like this:
a, b, c, , e, , g
If you would prefer to remove extra commas to output this:
a, b, c, e, g
Then add an ELSIF
check to the function like this:
CREATE FUNCTION commacat_ignore_nulls(acc text, instr text) RETURNS text AS $$
BEGIN
IF acc IS NULL OR acc = '' THEN
RETURN instr;
ELSIF instr IS NULL OR instr = '' THEN
RETURN acc;
ELSE
RETURN acc || ', ' || instr;
END IF;
END;
$$ LANGUAGE plpgsql;
How to use GROUP BY to concatenate strings while joining multiple tables?
You can specify a CTE – common table expression to store your temporary result :
with cteTbl ( CardID
, TechName
, problemReported ) as (
select j.CardID
, p.ProblemReported
, ( select TechnicianName
from easy_tbltechnicianMaster
where TechnicianID = t.technicianID ) as TechName
from easy_tbljobcard as j
join easy_technician as t on t.CardID = j.CardID
left join easy_tblproblem as p on p.CardID = t.CardID )
And then select
from it and concatenate all column values with the same t.techName
and t.CardID
in one row with for xml path('')
and after that replace the first comma ,
with stuff
:
select t.CardID
, t.TechName
, stuff( ( select ', ' + ProblemReported
from cteTbl
where TechName = t.TechName
order by ProblemReported
for xml path('') ), 1, 1, '') AS ProblemReported
from cteTbl t
group by t.TechName
, t.CardID
SQLFiddle
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