How to Use PQL to Query a SQLite Database

Anyquery is a SQL query engine that allows you to run SQL queries on virtually anything. One of its strengths is the ability to use alternative query languages, such as PQL (Portable Query Language), to query data. In this tutorial, you will learn how to use PQL to query a SQLite database.

Introduction to Anyquery

Anyquery uses SQLite as its core query engine and can connect to various data sources through plugins. With Anyquery, you can query data from databases, APIs, and even files. You can install Anyquery by following the instructions on the installation page.

Here's an example of querying a GitHub repository using SQL:

SELECT * FROM github_repositories_from_user('cloudflare') ORDER BY stargazers_count DESC;

Setting Up Anyquery with SQLite

Before we dive into PQL, let's set up Anyquery to work with a SQLite database:

  1. Install Anyquery: Follow the installation guide.
  2. Create a SQLite Database: You can create a SQLite database using SQLite command line or any SQLite GUI tool. For this example, let's assume you have a database file named example.db.

Enabling PQL in Anyquery

PQL (Portable Query Language) is a language similar to Microsoft Kusto Query Language (KQL). To enable PQL in Anyquery, run the following command:

anyquery --pql

Alternatively, you can switch to PQL after entering the shell mode by running:

.language pql

To switch back to SQL, run:

.language

Refer to the alternative languages documentation for more details.

Running PQL Queries on SQLite

Once PQL is enabled, you can start querying your SQLite database using PQL syntax. Here are some examples:

Example 1: Selecting All Rows from a Table

example_table
| project *

Example 2: Filtering Rows

example_table
| where age > 25
| project name, age

Example 3: Sorting Rows

example_table
| sort by age desc
| project name, age

Example 4: Limiting Rows

example_table
| take 10
| project name, age

Example 5: Aggregating Data

example_table
| summarize avg_age=avg(age) by department

Example 6: Joining Tables

Note: PQL does not directly support joins like SQL. To achieve this, you can use subqueries or CTEs.

with subquery1 as (
    select * from employees
),
subquery2 as (
    select * from departments
)
subquery1
| join subquery2 on subquery1.department_id == subquery2.id
| project subquery1.name, subquery2.department_name

Exporting Results

You can export query results to various formats such as JSON, CSV, etc. For example, to export the results to a JSON file:

anyquery -q "example_table | project * | take 10" --json > output.json

Refer to the exporting results documentation for more details.

Conclusion

You have learned how to use PQL to query a SQLite database with Anyquery. PQL offers a readable and intuitive syntax for querying data, making it a powerful alternative to SQL. Explore more features and plugins in the official documentation to unlock the full potential of Anyquery.