SQL Queries

 

🔹 Introduction

This page contains a collection of commonly used T-SQL examples for everyday database development and administration tasks in Microsoft SQL Server.Each example is explained clearly to help both beginners and experts improve productivity and query writing skills.

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📘 1️⃣ Database & Table Operations

➤ Create a Database

CREATE DATABASE SampleDB;

➤ Create a Table

CREATE TABLE Employees (
    EmpID INT PRIMARY KEY,
    EmpName VARCHAR(100),
    Department VARCHAR(50),
    Salary DECIMAL(10,2)
);

➤ Insert Data

INSERT INTO Employees (EmpID, EmpName, Department, Salary)
VALUES (1, 'John Doe', 'IT', 65000.00),
       (2, 'Sara Lee', 'HR', 52000.00);

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📊 2️⃣ Select & Filtering Queries

➤ Select All

SELECT * FROM Employees;

➤ Select with Filter

SELECT EmpName, Salary
FROM Employees
WHERE Department = 'IT';

➤ Sorting Results

SELECT * FROM Employees
ORDER BY Salary DESC;

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🔄 3️⃣ Update & Delete

➤ Update Data

UPDATE Employees
SET Salary = Salary + 5000
WHERE EmpID = 1;

➤ Delete Data

DELETE FROM Employees
WHERE EmpID = 2;

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🔁 4️⃣ Joins

➤ Inner Join Example

SELECT e.EmpName, d.DepartmentName
FROM Employees e
INNER JOIN Departments d
ON e.Department = d.DepartmentCode;

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🧠 5️⃣ Stored Procedure Example

CREATE PROCEDURE GetEmployeeByID
    @EmpID INT
AS
BEGIN
    SELECT * FROM Employees
    WHERE EmpID = @EmpID;
END;

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🏷 6️⃣ Useful System Queries

➤ Check SQL Server Version

SELECT @@VERSION;

➤ List All Databases

SELECT name FROM sys.databases;

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✔ Final Note

This page is updated regularly with new T-SQL examples covering:

• Performance Tuning

• Indexing

• CTE & Window Functions

• Backup & Restore

• Security and Administration Commands

Bookmark this page and check back often!