Green-Tree company launched a new campaign for the New Year and made different offers to its online customers. As a result of their campaign, they succeeded in converting some offers to sales. In the following examples, we will uncover the new year campaign data details of the Green-Tree company.
The company stores these campaign data details in the following tables. Now, we will create these tables through the following query and populate them with some dummy data:. In order to answer this question, we need to find out the matched rows for all the tables because some customers did not receive an email offer, and some offers could not be converted into a sale.
The following Venn diagram will help us to figure out the matched rows which we need. In short, the result of this query should be the intersecting rows of all tables in the query. The grey-colored area specifies these rows in the Venn diagram:. The SQL multiple joins approach will help us to join onlinecustomers , orders, and sales tables. As shown in the Venn diagram, we need to matched rows of all tables.
For this reason, we will combine all tables with an inner join clause. Listing 4. You might expect the result, Figure 4. But the row for publisher P03 located in Germany is missing because it contains a null in the column state. The null causes the result of both of the OR conditions to be unknown, so the row is excluded from the result.
NOT acts on one condition. To negate two or more conditions, repeat the NOT for each condition. The latter clause is legal but returns the wrong result. See the Tips in this section to learn ways to express equivalent NOT conditions. In comparisons, using NOT often is a matter of style.
The following two clauses are equivalent:. You can combine the three logical operators in a compound condition. You can override this order with parentheses: Everything in parentheses is evaluated first. When parenthesized conditions are nested, the innermost condition is evaluated first. AND is evaluated before OR , so the query is evaluated as follows:.
To see the result of each comparison in Listing 4. If your search condition contains only AND operators, your query will run faster if you put the conditions least likely to be true first. For search conditions that contain only OR operators, do the reverse: Put the most likely conditions first. If the conditions are equally likely, put the least complex expression first.
The logical meaning of OR finds books that meet any of the criteria, not all the criteria at the same time:. Table 4. In MySQL 4. You must master the laws in Table 4. For example, the statement. You also can use the laws to change a condition into its opposite. For example, the reverse of the condition.
In this case, it would have easier just to negate the entire original expression with NOT :. I would like to receive exclusive offers and hear about products from Peachpit and its family of brands. I can unsubscribe at any time. To get correct distances, you'd actually have to use some kind of proper distance function see e. But this SQL should give you an idea how to start:.
Based on comments throughout this question and answers so far, it sounds like you're looking for something more along the lines of this:. Note the OR between the top-level conditionals.
This is because you want records which are lat or long , since no single record will ever be lat and long. I'm still not sure what you're trying to accomplish by the inner conditionals. Any non-null value will match those numbers. So maybe you can elaborate on what you're trying to do there. Can we see the structure of your table?
That would explain why you don't get results when you connect the with an AND ; it's impossible. Stack Overflow for Teams — Collaborate and share knowledge with a private group.
Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 9 years, 10 months ago. Active 6 years, 11 months ago. Viewed k times. Thanks for the help in advance! Improve this question. Can you clarify specifically what happens when you "stitch them together"? This type of search requires an OR condition. Search for a book title that both starts with the word "The" and contains the word "Cook. The examples focus on creating WHERE clauses, but the principles apply to both types of search conditions.
To search for alternative values in the same data column, you specify an OR condition. To search for values that meet several conditions, you specify an AND condition.
Using an OR condition enables you to specify several alternative values to search for in a column. This option expands the scope of the search and can return more rows than searching for a single value.
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