SQLite Select Statement

SQLite is a C library that provides a lightweight, disk-based database. It allows us to create a standalone, zero-configuration, full-featured, SQL database engine. This makes it a very useful tool for storing small and embedded database engines.

The SELECT statement in SQL is a foundational command that plays a crucial role in a wide range of operations. It allows us to choose and display data from a given database.

In this tutorial, we will learn how we can use the SELECT statement in a SQLite database. We will also cover some practical examples of how to use it.

SQLite SELECT Statement

The SQLite SELECT statement allows us to fetch data from a database table. The query returns the matching data in the form of a SQL result table or result-sets.

Statement Syntax

The following statement below demonstrates the syntax of the SELECT statement in SQLite:

SELECT DISTINCT column_list
FROM table_list
JOIN table ON join_condition
WHERE row_filter
GROUP BY column
HAVING group_filter
ORDER BY column
LIMIT count OFFSET offset;

Let us break down the syntax above:

1. SELECT DISTINCT column_list - The SELECT statement allows us to select data from a database. The DISTINCT clause will force the query to only return the distinct values in the specified columns.
2. FROM table_list - This specifies the table from which to retrieve the data.
3. JOIN table ON join_condition - The JOIN clause allows us to combine rows from two or more tables, based on a related column between them. The ON keyword is used to specify the criterion for the join.
4. WHERE row_filter - The WHERE clause is used to filter records from the result set.
5. ORDER BY column - The ORDER BY keyword allows us to sort the result-set in ascending or descending order. The ORDER BY keyword sorts the records in ascending order by default, to sort the records in descending order, you can use the DESC keyword.
6. LIMIT count OFFSET offset - The LIMIT clause constrains the number of rows that are returned. The OFFSET keyword allows us to specify the starting point for the rows that are returned.
7. GROUP BY column - The GROUP BY statement allows us to apply an aggregate function in the result set (COUNT, MAX, MIN, SUM, AVG) to group the result-set by one or more columns.
8. HAVING group_filter - The. HAVING clause allows us to specify a condition for the grouped rows.

If you want to select all columns from the table, you can use the asterisk (*) symbol:

SELECT * FROM table_name;

Basic Examples

Let’s consider we have a table named Customers with the following data:

Here’s how you can use the SELECT statement to fetch data from this table:

• Example 1: To select all columns from the Customers table:

SELECT * FROM Customers;

This statement will return all rows in the table.

• Example 2: To select only the Name and Age columns:

SELECT Name, Age FROM Customers;

This statement will return all rows, but only the Name and Age columns.

SQLite SELECT Statement with WHERE Clause

The WHERE clause is used to filter records. It’s used to extract only those records that fulfill a specified condition.

Here’s the syntax:

SELECT column1, column2, ..., columnN 
FROM table_name 
WHERE condition;

For example, to select only the customers who live in “NY”:

SELECT * FROM Customers WHERE City = 'NY';

This statement will return the rows where the City is ‘NY’.

You can also use logical operators like AND and OR in the WHERE clause to combine more conditions:

SELECT * FROM Customers WHERE City = 'NY' AND Age > 30;

This will return the rows where the City is ‘NY’ and Age is greater than 30.

Conclusion

In this tutorial, we’ve explored the SQLite SELECT statement, including its basic usage and some practical examples. Using SELECT with SQLite (or any SQL database) is fundamental to retrieving the data that you need, and mastering its use is crucial to managing and analyzing your data efficiently.

Remember that practice is the key to mastering these concepts, so don’t hesitate to apply what you’ve learned here on some real-world databases. Happy querying!