What is the purpose of Array_To_String in PostgreSQL?

Answer:

The "Array_To_String" function concatenates array elements using provided delimiter.

Let us consider that we have two tables say Employee and Department with the below data.

/* Employee Table(tblEmployee) */

DeptId		EmpName	

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

1		Shashi Bhushan

1		Deepak Singh

1		Abhijeet Moshambique

1		Manish Bharat

2		Fatima  Sarani

2		Sumanta Manik

3		Amitav Mallik

3		Deepak Kumar Goyal

3		Amitav Salonki

4		Amit Ojha







/* Department Table(tblDept) */

DeptId		DeptName

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

1		Accounts

2		Finance

3		IT

4		Sales



*/

And we are looking for the below output

/* Result */

Deptname	Employee List

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

Accounts	Shashi Bhushan,Deepak Singh,Abhijeet Moshambique,Manish Bharat

Finance	Fatima  Sarani,Sumanta Manik

IT		Deepak Kumar Goyal,Amitav Salonki

Sales	Amit Ojha

We can achieve this by using Array_To_String function as under

SELECT DeptName, Array_To_String(Array_Agg(EmpName),',') "Employee List"

FROM tblEmployee 

Join tblDept

Using(DeptId) 

Group By DeptName;