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