# SQL COUNT(), AVG() and SUM() Functions

The SQL COUNT (), AVG () and SUM () functions are aggregate functions, which are used to perform calculation on multiple rows and return a single value.All aggregate functions by default exclude nulls values before working on the data.

**COUNT Function:**

COUNT Function is used to return total number of rows that matches a specified criteria.COUNT(*) also considers Nulls and duplicates.

**COUNT Function Syntax :**

The syntax of the COUNT Function is −

SELECT COUNT(column-name) FROM table-name WHERE condition;

**AVG() Functions :**

AVG Function is used to return average value of rows that matches a specified criteria.AVG() function works only on numeric data types.

**AVG() Functions Syntax :**

The syntax of the AVG() Functions is −

SELECT AVG(column-name) FROM table-name WHERE condition;

**SUM() Functions :**

SUM Function is used to return total sum of rows that matches a specified criteria. SUM only works on numeric fields. Null values are excluded from the returned result.

**SUM() Functions Syntax :**

The syntax of the SUM() Functions is −

SELECT SUM(column-name) FROM table-name WHERE condition;

**SQL COUNT(), AVG() and SUM() Example :**

Consider the Customer table with the following records -

CustomerID | CustomerName | Age | Address | CustomerSalary |
---|---|---|---|---|

1 | Aarav | 28 | Udaipur | 28000 |

2 | Vivaan | 25 | Mumbai | 30000 |

3 | Reyansh | 28 | Chennai | 35000 |

4 | Muhammad | 24 | Udaipur | 50000 |

5 | Sai | 30 | Mumbai | 27000 |

**COUNT Example**:- The following code is an example that will return the total customer IDs in the table.

SELECT COUNT(CustomerID) FROM Customer;

The result for the respective sql query is as follows −

COUNT(CustomerID) |
---|

5 |

**AVG Example**:-The following code is an example that will return the average of CustomerSalary in the table.

SELECT AVG(CustomerSalary) FROM Customer;

The result for the respective sql query is as follows −

AVG(CustomerSalary) |
---|

34000 |

**SUM Example**:- The following code is an example that will return the SUM of CustomerSalary in the table.

SELECT SUM(CustomerSalary) FROM Customer;

The result for the respective sql query is as follows −

SUM(CustomerSalary) |
---|

170000 |

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