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SQL Database User 1 SQL*Plus 2 Connect with System User 3 Create a new Database User 4 Log into new User

SQL Database 1 Create Database 2 Delete or Drop Database 3 Use Database 4 Create Database in SQL Server 5 Rename Database

SQL Table 1 Create Table in SQL Server 2 Delete or Drop table 3 Insert Data into table 4 Select Distinct 5 Select Top 6 Where Clause 7 Aliases 8 Update Table 9 AND, OR, NOT 10 IN 11 Between 12 Order By 13 Group By 14 Having 15 Exists 16 ANY and ALL 17 CASE Statement 18 Select Into 19 Alter Table 20 Order of execution of a Query 21 Create table

SQL Constraints 1 Constraints Introduction 2 Not Null 3 Unique 4 Primary Key 5 Foreign Key 6 Check 7 Default 8 Index 9 Auto Increment Field 10 Cascading referential integrity constraint 11 Identity Column in SQL Server

SQL Keywords 1 Keywords Introduction

SQL Data Types 1 Data Types Introduction

SQL Operators 1 Operators Introduction

SQL Wildcard Characters 1 Wildcard Introduction 2 Like

SQL Joins 1 Joins Introduction 2 Inner Join 3 Left Join 4 Right Join 5 Full Join 6 Self Join 7 Union 8 Cross Join 9 Advanced Join

SQL Aggregate Function 1 Introduction 2 Min 3 Max 4 Count 5 Avg 6 Sum

SQL Views 1 Views Introduction 2 Advantages of View 3 Updateable Views 4 Limitations of views

SQL Dates 1 Dates Introduction

SQL Stored Procedures 1 Stored Procedures Introduction 2 Advantages of Stored Procedures 3 Simple Store Procedure 4 Stored procedure with input parameters 5 Stored Procedure with OUTPUT Parameters 6 Alter Procedure

SQL Functions 1 Functions Introduction 2 Table Valued Functions 3 Scalar Valued Functions 4 Stored Procedure VS Function 5 Multi-Statement Table Valued Functions 6 Function WITH ENCRYPTION 7 Function WITH SCHEMABINDING

String Functions in SQL Server 1 Ascii() 2 Char() 3 Ltrim() 4 Rtrim() 5 Lower() 6 Upper() 7 Reverse() 8 Len() 9 Left() 10 Right() 11 CharIndex() 12 SubString() 13 Function Real time Example 14 Replicate() 15 Space() 16 Patindex() 17 Replace() 18 Stuff()

SQL Server Date Functions 1 ISDATE() 2 DAY() 3 MONTH() 4 YEAR() 5 DATENAME() 6 DATEPART() 7 DATEADD () 8 DATEDIFF() 9 Real time Example

Other Functions in SQL Server 1 Cast() 2 Convert()

Mathematical Functions in SQL Server 1 Mathematical Functions in SQL

Temporary tables 1 Local Temporary tables 2 Global Temporary tables

Indexes 1 Clustered Index 2 Non Clustered Index 3 Unique Index 4 Advantages and disadvantages of indexes

SQL Server Trigger 1 Triggers in SQL Server 2 After update trigger 3 Instead of insert trigger 4 Instead of update triggers 5 Instead of delete trigger 6 Common table expression (CTE)

Backup and Restore 1 Backup in SQL Server 2 Database Restore

SQL Introduction 1 About SQL Tutorial 2 SQL Basic Overview 3 Query Language 4 Microsoft SQL Server 5 MySQL 6 Oracle Database

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Mastering the COUNT() Aggregate Function in SQL: A Comprehensive Guide

Rumman Ansari July 19, 2024 6,086 views

Mastering the COUNT() Aggregate Function in SQL: A Comprehensive Guide

The COUNT() function returns the number of rows that matches a specified criteria.

The AVG() function returns the average value of a numeric column.

The SUM() function returns the total sum of a numeric column.

Syntax:


SELECT COUNT(column_name)
FROM table_name
WHERE condition;

We will apply COUNT function in this below table:

We will find the how may employee are available

EmpId	EmpName	EmpAddress	EmpSalary	EmpDept
11	Rambo	Kolkata	30000	ADMIN
21	Inza	Bihar	31000	SALES
32	Samser	Kolkata	32000	IT
41	Kamran	Hydrabad	33000	ITIS
52	Azam	Kolkata	33000	ITIS

Example: COUNT

Code:


SELECT COUNT(EmpId) AS NoOfEmployee FROM EmployeeDetails

Output:

The above code will produce the following result-


NoOfEmployee
5