Aggregate functions, you can also call column functions. Because you can use these functions only for Table columns. Below are the rules of aggregate functions.
The syntax.
AVG(SALARY) – Here SALARY is name of the column. Below is the list of rules.
Rule-1
A select query that uses Aggregate function called summary query.
Rule-2
The result of AVG and SUM functions is numeric. These functions only work with numerics.
Rule-3
The result of MIN, MAX and COUNT can be a numeric or DATE, or String value.
Rule-4
By default DUPLICATEs are considered. So use distinct to ignore duplicates.
Rule-5
You cannot mix aggregate and non-aggregate functions in SELECT statement. You need GROUP BY to mix both.
Rule-6
Aggregate functions ignore NULL values.
QUIZ
Try the tricky questions.
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