COMPUTER SCIENCE AND ENGINEERING
SQL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Yes
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No
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Either A or B
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None of the above
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Detailed explanation-1: -As we have seen from the above examples joining NULL values does not work. Even though you have two NULL values SQL Server does not treat these as the same value. Internally a value of NULL is an unknown value and therefore SQL Server does not equate an unknown value being equal to another unknown value.
Detailed explanation-2: -Null values in tables or views being joined will never match each other. Since bit columns do not permit null values, a value of 0 appears in an outer join when there is no match for a bit column that is in the inner table. The result of a join of NULL with any other value is NULL.
Detailed explanation-3: -The result of a join of null with any other value is null. Because null values represent unknown or inapplicable values, Transact-SQL has no basis to match one unknown value to another. You can detect the presence of null values in a column from one of the tables being joined only by using an outer join.