HomeProgramSQL ServerCOUNT function in SQL Server

COUNT function in SQL Server

This article will show you in detail how to use functions that handle COUNT () numbers in SQL Server with specific syntax and examples to better visualize and capture functions.

Describe

The COUNT function in SQL Server is used to count the number of records (data, rows) contained in a data table. The values ​​NULL omitted do not count.

Syntax

To use the COUNT function in SQL Server, we use the following syntax:

 SELECT COUNT(cot) 
 FROM bang 
 [WHERE dieukien];

Parameters :

  1. cot: column or calculated value, the expression you want to count
  2. state: the table used to retrieve the record. Must have at least 1 table in the FROM clause.
  3. dieukien: optional. Conditions that the record must meet to be selected.

Note :

  1. The COUNT function can be used in later versions of SQL Server: SQL Server 2017, SQL Server 2016, SQL Server 2014, SQL Server 2012, SQL Server 2008 R2, SQL Server 2008, and SQL Server 2005.

For example

Take a look and explore some examples of COUNT functions in SQL Server.

Suppose, we have the following data table:

COUNT function in SQL Server Picture 1

Example 1: Count the number of categories in the table

 SELECT COUNT(*) 
 FROM Quantrimang 
 WHERE Sobai > 100; 
 
 Result: 5

In this example we count the number of categories in the Quantrimang table that are larger than 100.

Example 2: Use DISTINCT

The DISTINCT and COUNT commands can be used together to count the number of duplicate results.

 SELECT COUNT(DISTINCT Sobai) 
 FROM Quantrimang 
 WHERE Sobai > 100; 
 
 Result: 4

This example uses the keyword DISTINCT, so the repeated values ​​are counted only once. In the given data table, the value '101' appears twice, but only once, so the total number of calculated lines will be 4.

Example 3: Using GROUP BY

The following example counts all records related to a large section and you will do the following:

 SELECT Chuyenmuclon, COUNT(Chuyenmuccon) AS "So luong" 
 FROM Quantrimang 
 GROUP BY Chuyenmuclon; 
 
 Result: 
 Chuyenmuclon So luong 
 Laptrinh 3 
 Mang xa hoi 2 
 Trinh duyet web 1

Previous article: CEILING function in SQL Server

Next lesson: FLOOR function in SQL Server

5 ★ | 1 Vote
mssql functionsql server number handling functionsql server math function

You should read it

May be interested

  • MAX function in SQL ServerPhoto of MAX function in SQL Server
    the article will explore and show you how to use the max function in sql server to find the maximum value in a set.
  • MIN function in SQL ServerPhoto of MIN function in SQL Server
    the article will explore and show you how to use the min function in sql server to find the smallest value in a set.
  • ROUND function in SQL ServerPhoto of ROUND function in SQL Server
    the article will give you detailed instructions on how to use the sql server round () function with the syntax and specific examples to make it easier to visualize and capture the function better.
  • SIGN functions in SQL ServerPhoto of SIGN functions in SQL Server
    the sign function in sql server is used to retrieve the sign of a number or the transmitted expression.
  • SUM function in SQL ServerPhoto of SUM function in SQL Server
    the sql server sum function returns the total value of a column, a data set, or an expression.
  • CURRENT_TIMESTAMP command in SQL ServerPhoto of CURRENT_TIMESTAMP command in SQL Server
    the sql server current_timestamp function returns the current date and time, in the format 'yyyy-mm-dd hh: mi: ss.mmm'.

SQL Server