| Operator | Its Function | Order of Precedence |
| NOT |
Negates or returns the opposite value of the conditional statement behind it. |
Evaluated before both "And" and "OR" |
| AND |
Used to Put more than one Logical operation together. |
Evaluated After NOT But before OR |
| OR |
Also used to put multiple operations together. |
Third in line after "NOT" and "AND" |
NOT: Not Negates the expression after it. It's like asking for one thing and getting the exact oppsite. As you can see, we first asked for those prices greater than 3 Oracle responded to our request correctly. Then we ran the exact query again with the NOT preceding the test condition. The result as you would expect is the opposite of the original.
AND: Use AND when you need to put two conditions together. Here we got a bit elaborate but we pulled several fields of data from three different tables where both conditions were true. We tested the Product_id from the Product Table to see if it matched the Proc_id from the Transaction table. Then we tested for those records whose Customer_ID from the Customer table matched the Cust_id in the transaction table. The returned data are those fields requested in the select clause, and where both conditions are true in the where clause.
OR: The or operator retrieves data where one OR the other condition is true. Here we test the customer_ID and the price of items. If either condition is true, the data is retrieved.
