MySQL COALESCE()

The COALESCE() function in MySQL is used to return the first non-null value in a list of expressions. It’s especially useful when you have multiple values and want to retrieve the first non-null value. The syntax for the COALESCE() function is as follows:

COALESCE(expression1, expression2, ..., expressionN)

• expression1, expression2, …, expressionN: A list of expressions that you want to evaluate.

The COALESCE() function evaluates these expressions in order from left to right and returns the first non-null value it encounters. If all expressions are null, it returns null.

Here’s an example of how to use the COALESCE() function:

SELECT COALESCE(column1, column2, column3, 'No value') AS result
FROM your_table;

In this example, the COALESCE() function checks the values in column1, column2, and column3 in the specified order. It returns the first non-null value or ‘No value’ if all three columns are null.

The COALESCE() function is useful for handling missing or null values in your SQL queries and returning a default value when necessary. It simplifies your queries and makes them more readable by avoiding complex IFNULL or CASE statements to handle null values.