Comparing Character String in SQL WHERE Clause

To compare a character string in a WHERE clause, you have to enclose the string in single quotation marks (‘ ‘). The following example searches an employee whose first name is JOHN. When you execute the statement, no rows will be returned, because character strings are case sensitive and should be entered according to the data stored in the table. Since the first name of the searched employee is saved as John in the database, changing the character string from JOHN to John will fetch the match, as shown in the output screenshot.

Alternatively, you can use the UPPER built-in function to match the provided value, like this: WHERE UPPER(first_name)=’JOHN’. In this condition, the UPPER function is used to first convert the column value to upper case before matching it with the provided value. 

    SQL Statement :

SELECT        first_name, last_name, salary  

FROM           employees                             

WHERE       first_name=’JOHN’;                

    Output :