Answers for "how in sql standard the like clause can be used"

sql where value like a or b

-- example
SELECT Id, ProductName, UnitPrice, Package
  FROM Product
 WHERE ProductName LIKE 'Cha_' OR ProductName LIKE 'Chan_'

what is like operator in sql

(Like) Operator for partial searches using wildcard '%' and '_'
For Example:
Select * From Employees
Where last_name LIKE '_a%';