how to update non existing row mysql code example

Example 1: how to update an attribute in MySQL

UPDATE table_name
SET variable = 'changed field', variable = 'another changed field'
WHERE firstline_name = 1;

Example 2: how to update rows from a table when certain conditions are met in mysql

UPDATE table_name
SET column1 = value1, column2 = value2
WHERE condition <= condition AND condition != condition;