Mysql case when 






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The standard defines the simple case as a transformation to a searched case—the rules described above remain valid. Put simply: case expressions evaluate to the of the first true. It can be used to evaluate a greater range of tests. When one is not defined, and no matches are made, is returned.
If the is null, the else clause applies. The first is to transform data from one set of values to another.
See which returns the same result as. A case expression can contain several when- then pairs. Should any right be infringed, it is totally unintentional. If this optimization affects a part of a case expression, the evaluation order gets disturbed. If else is omitted, else null is implicit. When using data-changing functions, for example, they might be called even if it is not strictly necessary—nevertheless you might see their side effects: the changed data. The number of parameters is not limited. Even though different evaluation procedures must produce the same result, different procedures may cause different side effects. Being an expression—rather than a control structure—means that case varies the result of formulas expressions based on conditions. Nevertheless there are cases that can lead to surprising side effects. The returned value is a result of comparison or condition evaluated.
SQL Tutorial - A good example is to test for valid values within expressions such as when you divide numbers.
Control Flow functions return a value for each row processed. The returned value is a result of comparison or condition evaluated. See which returns the same result as. The result is ordered by using column alias Continent. If the unit price is equal to or greater than 20, the product is in High Price group. If the current Unix timestamp modulo 2 is mysql case when, the query result is ordered by FirstName. So if you execute the query multiple times, you would normally get results in different orders. Info about modulo operator, refer to. Otherwise, return the ReportsTo value. This website is hosted by. No portion may be reproduced without my written permission. Software and hardware names mentioned on this site are registered trademarks of their respective companies. Should any right be infringed, it is totally unintentional.