SQL COALESCE: Handling Empty Data

In SQL, the COALESCE function can be used to assign values to empty data. It takes multiple parameters and returns the value of the first non-null parameter. Therefore, you can set the first parameter of the COALESCE function as the column that needs to be assigned a value, and the second parameter as the value to assign.

Here is an example:

UPDATE 表名
SET 列名 = COALESCE(列名, '赋值的值')
WHERE 条件;

In the above example, to assign a specified value (‘value to be assigned’) to empty data in a column in the table, you can use the UPDATE statement combined with the COALESCE function.