MySQL CONCAT_WS() function

CONCAT_WS() function

MySQL CONCAT_WS() function is used to join two or more strings with a separator. The separator specified in the first argument is added between two strings. The separator itself can be a string. If the separator is NULL the result is NULL.

This function is useful in -

• String concatenation: It allows you to concatenate multiple strings together into a single string.
• Handling empty or NULL values: CONCAT_WS() omits empty or NULL values and does not add the separator.

Syntax:

CONCAT_WS (separator, string1, string2,…)

Arguments:

Syntax Diagram:

MySQL Version: 8.0

Pictorial Presentation

Example of MySQL CONCAT_WS() function

The following MySQL statement adds the first argument and second argument with a separator ", ".

Code:

SELECT CONCAT_WS(',','1st string','2nd string');

Output:

mysql> SELECT CONCAT_WS(',','1st string','2nd string');
+------------------------------------------+
| CONCAT_WS(',','1st string','2nd string') |
+------------------------------------------+
| 1st string,2nd string                    | 
+------------------------------------------+
1 row in set (0.00 sec)

Example of MySQL CONCAT-WS() function with where clause

The following MySQL statement adds arguments (i.e. aut_id, aut_name, country and home_city) with a separator ",", if country of the author is not USA.

Code:

SELECT CONCAT_WS(',',aut_id,aut_name,country,home_city) 
FROM author 
WHERE country<>'USA'; 

Sample table: author

Output:

mysql> SELECT CONCAT_WS(',',aut_id,aut_name,country,home_city) 
    -> FROM author 
    -> WHERE country<>'USA';
+--------------------------------------------------+
| CONCAT_WS(',',aut_id,aut_name,country,home_city) |
+--------------------------------------------------+
| AUT001,William Norton,UK,Cambridge               | 
| AUT002,William Maugham,Canada,Toronto            | 
| AUT003,William Anthony,UK,Leeds                  | 
| AUT004,S.B.Swaminathan,India,Bangalore           | 
| AUT005,Thomas Morgan,Germany,Arnsberg            | 
| AUT007,Piers Gibson,UK,London                    | 
| AUT009,Marquis de Ellis,Brazil,Rio De Janerio    | 
| AUT011,John Betjeman Hunter,Australia,Sydney     | 
| AUT012,Evan Hayek,Canada,Vancouver               | 
| AUT013,E. Howard,Australia,Adelaide              | 
| AUT014,C. J. Wilde,UK,London                     | 
+--------------------------------------------------+
11 rows in set (0.00 sec)

MySQL CONCAT_WS(): Handling NULL Values

The following MySQL statement concatenate multiple values along with NULL. If any NULL value found the NULL values are automatically skipped.

Code:

SELECT CONCAT_WS(' - ', 'Apple', NULL, 'Orange');

Output:

CONCAT_WS(' - ', 'Apple', NULL, 'Orange')|
-----------------------------------------+
Apple - Orange                           |

MySQL CONCAT_WS(): Combining Columns with NULL as Default Value

The following MySQL statement demonstrate how to use the CONCAT_WS() function to concatenate strings together with a specified separator, handle NULL values, and combine columns in various scenarios.

Code:

SELECT CONCAT_WS(' ', first_name, COALESCE(middle_name, 'N/A'), last_name) AS full_name 
FROM emp_test;

Sample table: emp_test

Output:

full_name   |
------------+
Jhon De Wood|
Piter   Van |
Monti       |
Mitchel N/A |

Difference between MySQL GROUP_CONCAT() and CONCAT_WS()

GROUP_CONCAT() function returns a string with concatenated non-NULL value from a group.
CONCAT_WS() function is used to add two or more strings with separator

See the following example:

mysql> SELECT userid, fname, lname  FROM user_details;

+----------+--------+---------+
| userid   | fname  | lname   |
+----------+--------+---------+
| scott123 | Scott  | Rayy    |
| ferp6734 | Palash | Ghosh   |
| diana094 | Diana  | Lorentz |
| abcd123  | John   | ray     |
+----------+--------+---------+
4 rows in set (0.00 sec)

mysql> SELECT GROUP_CONCAT(CONCAT_WS(' ', fname,lname)) FROM user_details ORDER BY userid ASC;

+------------------------------------------------+
| GROUP_CONCAT(CONCAT_WS(' ', fname,lname))      |
+------------------------------------------------+
| Scott Rayy,Palash Ghosh,Diana Lorentz,John ray |
+------------------------------------------------+
1 row in set (0.03 sec)

Here CONCAT_WS() insert a space as a separator between fname and lname while GROUP_CONCAT() returns the result in a single string.

Video Presentation:

All String Functions (Slides presentation)

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