Check the below input data and expected output and get the list of distinct concat string values.

Input Data:

id          strname
----------- ------------
1           abc
2           xyz
3           abc
4           pqr
5           pqr
6           xyz
7           wre
8           abc
9           wre

Expected Output:

result
-----------------------
abc, pqr, wre, xyz,

Create a table with sample data:

CREATE TABLE tbl_strings (id int, strname varchar(50))
GO

INSERT INTO tbl_strings VALUES 
(1,'abc'),(2,'xyz'),(3,'abc')
,(4,'pqr'),(5,'pqr'),(6,'xyz')
,(7,'wre'),(8,'abc'),(9,'wre')
GO

Solution using XML PATH:

SELECT DISTINCT strname + ', '
FROM tbl_strings
FOR XML PATH('')

Please try the different solution for this puzzle and share it via comment...

Check the below input data and expected output and concat the string data without using STUFF function.

Input Data:

id          strname
----------- ------------
1           a
1           b
1           c
2           x
2           y
3           p
3           q
3           r

Expected Output:

id          ConcatString
----------- ---------------
1           a, b, c
2           x, y
3           p, q, r

Create a table with sample data:

CREATE TABLE tbl_strings (id int, strname varchar(50))
GO

INSERT INTO tbl_strings VALUES 
(1,'a'),(1,'b'),(1,'c')
,(2,'x'),(2,'y')
,(3,'p'),(3,'q'),(3,'r')
GO

Solution by creating a function:

CREATE FUNCTION [dbo].[GetConcatString]
(
    @id int
)
RETURNS varchar(max)
AS
BEGIN
    DECLARE @str VARCHAR(max)
    SELECT @str = COALESCE(@str + ', ', '') + strname
    FROM tbl_strings
    WHERE id = @id
    RETURN @str
END
GO

SELECT id, dbo.GetConcatString(id) as ConcatString
FROM tbl_strings
GROUP BY id
GO

Please try the different solution for this puzzle and share it via comment...

The PostgreSQL JSON data type is also one of the my favorite topic.
I have written multiple article on PostgreSQL JSON data type.

PostgreSQL 9.4: The JSON data type is Awesome (Part 1/3)

PostgreSQL 9.5 introduced one new operator (||) which used to perform Concatenate and Overwrite of JSON Document.

The requirement is something like: we have stored one JSON string or document into PostgreSQL. Now we require to add any new key or elements into that document.

It was not possible in the previous version of PostgreSQL, but now we can use (||) this operator to add or overwrite particular key into the JSON document.

Please go through this full practical demonstration:

Create a table with Sample data:

CREATE TABLE tbl_TestJSON
(
	ID INTEGER PRIMARY KEY
	,DepartName VARCHAR(250)
	,EmployeeDetails JSONB
	,Address JSONB
);

INSERT INTO tbl_TestJSON
VALUES 
(
	1
	,'Sales'
	,'
	{"employees":[
	    {"firstName":"Anvesh", "lastName":"Patel"},
	    {"firstName":"Eric", "lastName":"Marin"},
	    {"firstName":"Martin", "lastName":"Loother"}
	]}'
	,'{"address" : "Hyderabad"}'
)
,(
	2
	,'Production'
	,'
	{"employees":[
	    {"firstName":"Neevan", "lastName":"Patel"},
	    {"firstName":"Roy", "lastName":"Boon"},
	    {"firstName":"Nancy", "lastName":"Shah"}
	]}'
	,'{"address" : "Ahmedabad"}'
);

Using (||) operator can concat two JSON String:
In the below example, you can see “address” key is merged with “employees” key.

SELECT EmployeeDetails || Address AS JsonData FROM tbl_TestJSON;
/*
		   JsonData
------------------------------------------------
{"address": "Hyderabad"
 ,"employees": 
	[{"lastName": "Patel", "firstName": "Anvesh"}
	,{"lastName": "Marin", "firstName": "Eric"}
	,{"lastName": "Loother", "firstName": "Martin"}
	]
}
{"address": "Ahmedabad"
 ,"employees": 
	[{"lastName": "Patel", "firstName": "Neevan"}
	,{"lastName": "Boon", "firstName": "Roy"}
	,{"lastName": "Shah", "firstName": "Nancy"}
	]
}*/

Using (||) operator can overwrite the JSON string:
In the below example, you can see the replacement of “address” value.

SELECT EmployeeDetails || Address || '{"address": "Pune"}'FROM tbl_TestJSON;
/*
		  JsonData
-------------------------------------------------
{"address": "Pune"
 ,"employees": 
	    [{"lastName": "Patel", "firstName": "Anvesh"}
	    ,{"lastName": "Marin", "firstName": "Eric"}
	    ,{"lastName": "Loother", "firstName": "Martin"}
	    ]
}
{"address": "Pune"
 ,"employees": 
	   [{"lastName": "Patel", "firstName": "Neevan"}
	   ,{"lastName": "Boon", "firstName": "Roy"}
	   ,{"lastName": "Shah", "firstName": "Nancy"}
	   ]
}*/

The SQL Server 2012 introduced the new CONCAT function for the concatenation of the string and integer value.

Previously, we were doing concatenation using ‘+’ operator and using COALESCE().
But this newly introduced CONCAT() is faster than any other approach for the concatenation techniques.

The syntax of CONCAT():

CONCAT ( string_value1, string_value2 [, string_valueN ])

Different example of CONCAT():

CONCAT string values:

SELECT CONCAT('Database ','Research ','& ','Development') AS ConcatString

ConcatString
-------------------------------
Database Research & Development

(1 row(s) affected)

CONCAT integer values:

SELECT CONCAT(8,8,2) AS ConcatInteger

ConcatInteger
----------------
882

(1 row(s) affected)

CONCAT decimal values:

SELECT CONCAT(25.36,4.8) AS ConcatDecimal

ConcatDecimal
-------------------------------------------
25.364.8

(1 row(s) affected)

CONCAT with NULL:

SELECT CONCAT('Database Research ','& Development',NULL) AS ConcatStringWithNull

ConcatStringWithNull
-------------------------------
Database Research & Development

(1 row(s) affected)

Invalid CONCAT parameters:

SELECT CONCAT('Database Research & Development ') AS ConcatError
Msg 189, Level 15, State 1, Line 1
The concat function requires 2 to 254 arguments.