CONDITIONALS are operators which allow you to get more specific (or general) in your query.
- =: equals
- <: less than
- >: greater than
- <=: less than or equal to
- >=: greater than or equal to
- !=: not equal to
- IS NOT NULL: has any value
- IS NULL: has no value at all
- BETWEEN: within a specified range
- NOT BETWEEN: outside of a specified range
- OR: one of two equations are true
- ||: same as OR
- AND: both equations are true
- &&: same as AND
- NOT: both equations are false
- !: same as NOT
The query will only pick out the rows that provide a TRUE result according to the WHERE equation. In this case, there would be TWO parts that must be true to return a result. Example...
The query would search the address_book table and compare all of the data in the first_name column AND the last_name column for the specified values. The WHILE loop then prints out the results found if both equations are found TRUE.