AGGREGATE FUNCTIONS DBMS

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 In DBMS, aggregate functions are used to combine multiple values of rows to get a single meaningful value. 

Various Aggregate functions are:

Count():

  • Count(*): Returns the total number of records
  • Count(column_name): Returns the total number of non-null values in the column.
  • Count(distinct column_name): Returns the total number of distinct non-null values in the column.

Sum():

  • Sum(column_name): Sum of all non-null values in the column
  • Sum(distinct column_name): Sum of all distinct non-null values in the column

Avg():

  • Avg(salary) = Sum(salary) / count(salary) = 310/5
  • Avg(Distinct salary) = sum(Distinct salary) / Count(Distinct Salary) = 250/4

 

Min():

  • Min(salary): Minimum value in the salary column except
    NULL i.e., 40.
  • Max(salary): Maximum value in the salary i.e., 80.

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