SQL by Example by John Russo

Author:John Russo
Language: eng
Format: epub
Publisher: Momentum Press

If we did not follow an order of precedence, we would get different results:

D = true or true and false

D = true and false

D = false

Let’s look at a few more examples.

3.7.1 EXAMPLE 3.6

Management would like a report that will show all shipments that originated in Seattle or Boston. For those shipments that originated in Boston, management only wants to see the ones that had captain 001-24 as the captain. Figure 3.6 shows our query and the results.

Figure 3.6. Query of shipments that originated in Boston and had captain 001-24 as captain.

Notice that the order of precedence dictated that the Boston and capt_id = ‘001-24’ were evaluated first, and then the or was evaluated next.

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