If they are not equal, the function returns the first expression.

If they are equal, the function returns null. NULLIF() : The NULLIF function compares two expressions.In simple words COALESCE() function returns the first non-null expression in the list.ĬOALESCE(commission_pct, salary, 10) comm The advantage of the COALESCE() function over the NVL() function is that the COALESCE function can take multiple alternate values. COALESCE() : The COALESCE() function examines the first expression, if the first expression is not null, it returns that expression Otherwise, it does a COALESCE of the remaining expressions.If the default value is omitted, a null value is returned where a search value does not match any of the result values. If the expression is the same as search, result is returned. The DECODE function decodes expression after comparing it to each search value. The DECODE function decodes an expression in a way similar to the IF-THEN-ELSE logic used in various languages. DECODE() : Facilitates conditional inquiries by doing the work of a CASE or IF-THEN-ELSE statement.SELECT last_name, salary, commission_pct, The argument expr1 can have any data type.Įxpr1 is the source value or expression that may contain nullĮxpr2 is the value returned if expr1 is not nullĮxpr3 is the value returned if expr1 is null If expr1 is not null, NVL2 returns expr2. If the first expression is null, then the third expression is returned i.e. If the first expression is not null, then the NVL2 function returns the second expression. NVL2(expr1, expr2, expr3) : The NVL2 function examines the first expression.ISRO CS Syllabus for Scientist/Engineer Exam.ISRO CS Original Papers and Official Keys.GATE CS Original Papers and Official Keys.

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