Concatenating Row Values into one column in Oracle, SQL Server Database and LINQ

Concatenating Row Values into one column in Oracle, SQL Server Database and LINQ Concatenating row values is very common requirements in different databases, to write this kind of query is very time consuming, I tried to combine Oracle,SQL Server database and LINQ simple solution into below example. Maybe this is not matched with your requirement but you will get an idea to proceed. Requirement Let say you have one Employee table having FK reference with department table like below Employee table EMP_ID DEPT_ID 1 101 2 101 3 102 4 102 5 102 How to write a select query so that it returns two columns DEPT_ID and Comma Separated employees under that department. Example DEPT_ID EMPLOYEES 101 1,2 102 3,4,5 Solution (ORACLE DATABASE) To achieve above requirement there are different solution available in oracle different versions Oracle 10g: Use COLLECT function like SELECT DEPT_ID, CAST (COLLECT (TO_CHAR(EMP_ID)) AS SYS.ODCIVARCHAR2LIST) AS EMPLOYEES FROM EMPLOYEE GROUP BY DEPT_ID Note: If SYS.ODCIVARCHAR2LIST does not work then you have to create one table object, see below example CREATE OR REPLACE TYPE Collect_Type AS TABLE OF VARCHAR2 (4000); SELECT DEPT_ID, CAST (COLLECT (TO_CHAR(EMP_ID)) AS Collect_Type) AS EMPLOYEES FROM EMPLOYEE GROUP BY DEPT_ID Oracle 11g: Use LISTAGG function like SELECT DEPT_ID, LISTAGG (TO_CHAR(EMP_ID), ', ') WITHIN GROUP (ORDER BY DEPT_ID)as "EMPLOYEES" FROM employees; Ref: http://download.oracle.com/docs/cd/E11882_01/server.112/e10592/functions087.htm Result: DEPT_ID EMPLOYEES 101 1,2 102 3,4,5 Solution (SQL SERVER DATABASE) SQL Server: SQL server database also you can achieve same result in multiple ways, like XML PATH or Custom Function etc. Using XML PATH Select Main.Dept_ID, Left(Main.Employee,Len(Main.Employee)-1) As "Employees" From(Select distinct ST2.Dept_ID, (Select cast(ST1.Emp_ID as varchar(50)) + ',' AS [text()] From dbo.Employee ST1 Where ST1.Dept_ID= ST2.Dept_ID ORDER BY ST1.Dept_ID For XML PATH ('')) [Employee] From dbo.Employee ST2) [Main] Using Custom Function CREATE FUNCTION ConcatEmp(@DeptId varchar(50)) RETURNS VARCHAR(1000) AS BEGIN DECLARE @temp VARCHAR(1000) SELECT @temp = COALESCE(@temp + ', ', '') + cast(Emp_ID as varchar(50)) FROM [Employee] WHERE Dept_ID = @DeptId return @temp END After creating above function you can simply execute in select statement like below SELECT Dept_ID , dbo.ConcatEmp(Dept_ID) AS Employees FROM Employee GROUP BY Dept_ID Result: DEPT_ID EMPLOYEES 101 1,2 102 3,4,5 Solution (LINQ QUERY) LINQ is one of the .NET (Framework 3.0 and above) features to write SQL query in code, if you are trying to achieve same result using LINQ, you can get idea from following example Here I have created one small console application and write following code to get same results as SQL Server and Oracle Database using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication1 { public class Test { static void Main() { var Employee = new[] { new { Dept="101", EmpId="1" }, new { Dept="101", EmpId="2" }, new { Dept="102", EmpId="3" }, new { Dept="102", EmpId="4" }, new { Dept="102", EmpId="5" }, }; var groupedUsers = Employee.GroupBy(Dept => Dept.Dept); foreach (var group in groupedUsers) { Console.Write(" {0} :", group.Key); foreach (var entry in group) { Console.Write(" {0}", entry.EmpId); } Console.WriteLine(); } Console.Read(); } } } Result: ---------- 101: 1,2 102: 3,4,5