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POShort-circuit logic evaluation operators
 

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    <p>Are there any short-circuit logic operators (specifically short-circuit <code>AND</code> and short-circuit <code>OR</code>) that I can use in a <code>WHERE</code> clause in MySQL 5.5? If there isn't, what are the alternatives?</p> <p>An abstract view at my problem along with an explanation as to why I need this can be found at this fiddle:</p> <p><a href="http://sqlfiddle.com/#!2/97fd1/3" rel="nofollow">http://sqlfiddle.com/#!2/97fd1/3</a></p> <p>In reality we are looking at millions of books in millions of bookstores in thousands of cities in hundreds of countries, which is why we cannot accept the overhead of receiving the unneeded information with every query we dispatch and seriously need to find a way to make the evaluation stop as soon as we have all rows that satisfy the current condition, before moving on to the next OR.</p> <p>Let me know if you need more information. Thanks in advance.</p> <hr> <p>As requested, here is the schema used in the fiddle:</p> <pre><code>CREATE TABLE quantitycache ( id INT AUTO_INCREMENT, quantity INT, book_id INT NOT NULL, bookstore_id INT NULL, city_id INT NULL, country_id INT NULL, PRIMARY KEY (id) ); </code></pre> <p>As well as some example data:</p> <pre><code>INSERT INTO quantitycache (quantity, book_id, bookstore_id, city_id, country_id) VALUES (5, 1, 1, NULL, NULL), (100, 2, 1, NULL, NULL), (7, 1, 2, NULL, NULL), (12, 1, NULL, 1, NULL), (12, 1, NULL, NULL, 1), (100, 2, NULL, 1, NULL), (100, 2, NULL, NULL, 1), (200, 3, NULL, 1, NULL), (250, 3, NULL, NULL, 1); </code></pre>
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    1. USChristian Kiewiet
    1. USChristian Kiewiet
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    1. COThe only way you are going to be able to do this is using T-SQL me thinks. If you write a query that queries ALL stores then you will have a long wait BUT with T-SQL you can set variables and flags etc to break out of a loop that iteratively executes a smaller portion of the query (i.e. query store by store) once a match is found.
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      1. USPaul Sullivan
    2. COI'll bet that it will stop evaluating an `OR` expression as soon as one of the cases matches, as long as none of the expressions has side effects.
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      1. USBarmar
    3. CO@Barmar: This is not true unfortunately, as you can see in the fiddle, the rows that satisfy the other OR conditions are returned as well.
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      1. USChristian Kiewiet
 

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