The COALESCE() function
The GREATEST() & LEAST() functions
The NULLIF() function
Instruction
Excellent! It's good to remember that COALESCE() takes an argument of only one data type. For instance, the following works fine:
SELECT COALESCE(price, 0.00) AS price FROM product;
The price column is of decimal data type; therefore we replace its 0.00 value which is the same data type. This function will return 0.00 in place of a NULL value in the price column.
Check it out yourself. Try to use the COALESCE() function to show the product name and the launch_date or 'no date' when the date is unknown.
Exercise
Run the template query. When you're done, click to continue.
