SQL Server Query Examples: SELECT, JOIN, GROUP BY, and More

10 Essential SQL Queries for SQL Server Beginners

1. SELECT basic columns

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SELECT FirstName, LastName, Email FROM Employees;

• Use: retrieve specific columns.

2. SELECT with WHERE

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SELECT 
FROM Orders WHERE OrderDate >= ‘2023-01-01’ AND CustomerID = 42;

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SELECT ProductName, Price FROM Products ORDER BY Price DESC;

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SELECT CustomerID, COUNT() AS OrderCount, SUM(TotalAmount) AS TotalSpent FROM Orders GROUP BY CustomerID;

• Use: aggregate per group.

5. HAVING to filter groups

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SELECT CustomerID, COUNT() AS OrderCount FROM Orders GROUP BY CustomerID HAVING COUNT() > 5;

• Use: filter aggregated groups.

6. JOIN (INNER JOIN)

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SELECT o.OrderID, c.CustomerName, o.OrderDate FROM Orders o INNER JOIN Customers c ON o.CustomerID = c.CustomerID;

• Use: combine related tables.

7. LEFT JOIN (include unmatched)

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SELECT c.CustomerName, o.OrderID FROM Customers c LEFT JOIN Orders o ON c.CustomerID = o.CustomerID;

• Use: get all left-side rows even with no match.

8. INSERT single row

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INSERT INTO Products (ProductName, Price, Stock)
VALUES (‘Widget’, 9.99, 100);

• Use: add a new record.

9. UPDATE rows

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UPDATE Products SET Price = Price * 1.05
WHERE Category = ‘Office’;

• Use: modify existing data.

10. DELETE rows safely

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DELETE FROM Sessions WHERE LastActive < ‘2024-01-01’;

• Use: remove rows; run a SELECT with the same WHERE first to confirm.

Tips:

• Always back up or run transactions for destructive queries.
• Use parameterized queries from applications to avoid SQL injection.
• Use SET NOCOUNT ON in scripts to reduce extra messages.