SQL Select Operation

A SELECT operation in SQL is used to retrieve data from one or more tables in a database. It allows you to specify the columns you want to retrieve, apply filters to narrow down the results, and even perform calculations or transformations on the data.

Here's the basic syntax for a SELECT statement:
SELECT column1, column2, ...
FROM table_name
WHERE condition;

Let's break down each part:

SELECT: This keyword indicates that you're selecting data from a table or tables.
column1, column2, ...: These are the names of the columns you want to retrieve data from. You can specify "*" to select all columns.
FROM: This keyword specifies the table or tables from which you want to retrieve data.
table_name: This is the name of the table you want to retrieve data from.
WHERE: This keyword is used to specify conditions that the retrieved data must meet. It's optional.
condition: This is the condition that the data must satisfy to be included in the result set. It can involve comparisons, logical operators, etc.

Here are some examples:

1. Selecting all columns from a table:
SELECT * FROM. Customer;
2. Selecting specific columns:
SELECT first_name, last_name FROM Customer;
3. Applying filters using WHERE clause:
SELECT * FROM orders WHERE order_date >= '2022-01-01';
4. Using functions and aliases:
SELECT product_name, unit_price * quantity AS total_price FROM order_details;