The case statement has two flavors. The simple case and the searched case. In the simple case the expression is written only once and depending on the result of this expression one of the possible cases is being used. This can be helpful when you need to choose from a set of distinct values. In the searched case every case has its own expression. This can for instance be helpful when using ranges. The else clause is optional.
NULL values are one of the most mind-boggling values in the Oracle database. Find out more. Fortnightly newsletters help sharpen your skills and keep you ahead, with articles, ebooks and opinion to keep you informed.
View all articles by Patrick Barel. FROM emp t. WHERE t. NVL expr1 , expr2. NVL2 expr1 , expr2 , expr3. LNNVL condition. FROM emp e. AND e. Penguin', 50, , null, 10 ; insert into toys values 2, 'Blue Brick', 10, null, 10, null ; insert into toys values 3, 'Red Brick', 20, null, 20, 1 ; commit;. Module 1. Introduction The table contains rows with several null values. Module 2. Nothing equals null! Null is neither equal to nor not equal to anything.
Module 3. Is null condition To find rows that have a null-value, use the "is null" condition. Module 4. Module 5. Module 6. Null functions Oracle Database includes many functions to help you handle nulls.
NVL This takes two arguments. It returns the first non-null value it finds: select t. Oracle also considers two nulls to be equal if they appear in compound keys. That is, Oracle considers identical two compound keys containing nulls if all the non-null components of the keys are equal. Table shows examples of various evaluations involving nulls in conditions.
Table Conditions Containing Nulls. For the truth tables showing the results of logical conditions containing nulls, see Table , Table , and Table
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