SQL Coalesce | Coalesce function in sql - sql - sql tutorial - learn sql
- Evaluates the arguments in order and returns the current value of the first expression that initially does not evaluate to NULL.
- The COALESCE function in SQL returns the first non-NULL expression among its arguments. The syntax for COALESCE is as follows:
- It is the same as the following CASE statement:
- For examples, say we have the following table,
- Table Contact_Info
- and we want to find out the best way to contact each person according to the following rules:
- If a person has a business phone, use the business phone number.
- If a person does not have a business phone and has a cell phone, use the cell phone number.
- If a person does not have a business phone, does not have a cell phone, and has a home phone, use the home phone number.
- We can use the COALESCE function to achieve our goal: