USING

MySQL

Example

SELECT * FROM Employees;

Output

| ID | Name | Department |
|----|------|------------|
| 1  | Amy  | HR         |
| 2  | Ben  | Finance    |
| 3  | Carl | IT         |

Explanation

In this SQL statement, SELECT * FROM Employees; is executed, which selects all the data from the Employees table. The ‘Output’ section shows the table displaying the result of the previous SQL statement. The table includes columns ‘ID’, ‘Name’, ‘Department’. The rows show the data of each employee in the ‘Employees’ table.

PostgreSQL

Example

CREATE TABLE Employees (
    ID INT PRIMARY KEY NOT NULL,
    NAME TEXT NOT NULL,
    AGE INT NOT NULL,
    ADDRESS CHAR(50)
);
INSERT INTO Employees (ID,NAME,AGE,ADDRESS) VALUES (1, 'Tom', 25, '1234 Main St');
SELECT * FROM Employees;

Output

|  ID | NAME | AGE | ADDRESS     |
|----:|:----:|:---:|:-----------:|
| 1   | Tom  |  25 | 1234 Main St|

Explanation

The SQL code defines a table ‘Employees’ and inserts a record into it. The output shows the resulting table as rendered in markdown, with one record for employee ‘Tom’.

Oracle

Example

SELECT 'Hello, World!' AS Greeting FROM dual;

Output

GREETING
----------------
Hello, World!

Explanation

The SELECT statement retrieves values from the database. Here, a string ‘Hello, World!’ is selected and given the alias Greeting. The FROM clause indicates the table where the SQL statement will look for the data. In Oracle, Dual is a special one-row, one-column table present by default. The output is a single record with a single column named Greeting that contains the string ‘Hello, World!’.

SQLite

Example

Markdown:

SELECT * FROM Employees WHERE Salary > 50000;

Output

Markdown:

Employee_ID	First_Name	Last_Name	Salary
3	John	Doe	60000
5	Jane	Smith	75000

Explanation

The SELECT command is used to select data from a database. Here, it selects all the fields (*) from ‘Employees’ table where the ‘Salary’ field is greater than 50000. The result is a table that includes rows for ‘Employee_ID’, ‘First_Name’, ‘Last_Name’ and ‘Salary’ where the salary is more than 50000.