SQL Query Pro-SQL Query Assistance

Example

SELECT Employees.name, Sales.amount FROM Employees JOIN Sales ON Employees.id = Sales.employee_id WHERE Sales.date BETWEEN '2021-01-01' AND '2021-12-31';

Scenario

Used to combine data from the Employees and Sales tables to analyze employee sales performance over a year.

Example

SELECT name, COUNT(*) AS num_sales FROM Sales JOIN Products ON Sales.product_id = Products.id GROUP BY name ORDER BY num_sales DESC LIMIT 10;

Scenario

Optimizes data retrieval to identify the top 10 best-selling products, efficiently handling large datasets and reducing server load.

Example

SELECT region, SUM(sales) AS total_sales FROM Sales GROUP BY region;

Scenario

Aggregates sales data by region to provide a summary report of sales performance across different geographical areas.

Example

ALTER TABLE Orders ADD CONSTRAINT FK_CustomerID FOREIGN KEY (CustomerID) REFERENCES Customers(ID);

Scenario

Ensures the integrity of the database by establishing a foreign key relationship, preventing orders from being placed for non-existent customers.