MySQL CONCAT_WS() Function

 The CONCAT_WS() function in MySQL is used to concatenate (combine) strings with a specified separator. It is a more flexible version of the CONCAT() function, as it allows you to specify a delimiter (separator) to insert between each string.

Syntax:

CONCAT_WS(separator, string1, string2, ..., stringN)

• separator: The string to use as a separator between the values being concatenated.
• string1, string2, ..., stringN: The strings to concatenate.

Key Features:

1. Separator Insertion: The separator is added between each of the strings provided as arguments.
2. Automatic Null Handling: If any of the strings are NULL, they are skipped. The separator is not added for skipped values.

Examples:

1. Basic Usage

SELECT CONCAT_WS('-', '2024', '12', '20');
-- Output: '2024-12-20'

2. Skipping NULL Values

SELECT CONCAT_WS('-', '2024', NULL, '20');
-- Output: '2024-20'

3. Combining Table Columns

Suppose you have a table employees:

first_name	last_name
John	Doe
Jane	Smith

You can combine the names with a space as a separator:

SELECT CONCAT_WS(' ', first_name, last_name) AS full_name
FROM employees;
-- Output: 
-- full_name
-- John Doe
-- Jane Smith

Notes:

• The CONCAT_WS() function is particularly useful when formatting output that requires separators, such as creating CSV lines, constructing file paths, or formatting dates and times.
• If you pass only the separator and no other arguments, the function will return an empty string.