SQLite Syntax: A Complete Beginner’s Guide

SQLite is a widely used open-source relational database management system.

Its lightweight and self-contained nature makes SQLite a popular choice for many applications.

While SQLite uses a dialect of SQL syntax, there are some key differences from standard SQL that developers should understand.

In this article, we’ll cover the basics of SQLite syntax and usage from the perspective of an experienced developer.

Quick Introduction to SQLite

SQLite uses a simplified SQL syntax that is optimized for embedded applications. While more limited than full SQL implementations, SQLite supports the core features needed for most database operations:

• Creating and altering table schemas – SQLite lets you create tables, define columns with data types, add and remove columns, create indexes, and make other schema changes.
• Inserting, updating, and deleting data – All the essential data manipulation statements like INSERT, UPDATE, and DELETE are supported.
• Querying and filtering data -SQLite includes WHERE, GROUP BY, JOIN, and other clauses for querying and filtering data.
• Creating views and triggers – SQLite also lets you develop VIEWs and Triggers like other SQL databases for commonly used queries or data logic.

Unlike client/server SQL databases, SQLite offers a much simpler setup and deployment. The entire database is stored in a single file, requiring no configuration of services. This makes SQLite a popular embedded database option for desktop and mobile apps. Now let’s dive into the syntax basics.

SQLite Basic Syntax

SQLite syntax is designed to be familiar to users of other SQL dialects. Here’s a quick overview of the basic statements:

Creating Tables

CREATE TABLE table_name ( column1 datatype, column2 datatype, column3 datatype );

• The column names and defined data types match standard SQL.
• Common datatypes include TEXT, INTEGER, REAL (float), BLOB, etc.

Inserting Data

INSERT INTO table_name (column1, column2) VALUES ($value1$, $value2$);

• Values are specified as $value$ placeholders.
• Alternatively, you can insert data for all columns without specifying column names.

Updating Records

UPDATE table_name SET column1 = $newvalue$ WHERE condition;

• The SET clause specifies the new values to update to.
• The WHERE clause filters which rows to update.

Deleting Records

DELETE FROM table_name WHERE condition;

• Again any rows matching the WHERE condition will be deleted.
• Omit the WHERE to delete all rows.

Selecting Data

SELECT column1, column2 FROM table_name WHERE condition ORDER BY column1;

SQLite includes full support for SELECT statements with joins, filtering, sorting, etc.

Altering Tables

ALTER TABLE table_name ADD column datatype;

• ALTER TABLE is used to add columns, create indexes, rename or drop columns.

Dropping Tables

DROP TABLE table_name;

This covers the basics of data definition and manipulation in SQLite syntax. With these statements, you can build complete applications leveraging SQLite’s efficient querying and data management.

SQLite Operators

SQLite supports most standard SQL comparison operators like =, !=, <, >, etc. It also includes some additional useful operators:

• $ in front of values acts as a placeholder variable.
• IS NULL and IS NOT NULL check for NULL values.
• Logical operators AND, OR, NOT can combine multiple conditionals.

For example:

SELECT * FROM table WHERE value $operator$ $value$ AND othercol IS NOT NULL

The $operator$ could be =, <, >, etc and $value$ is a variable placeholder. Multiple conditions can be specified using AND/OR.

Also read: SQLite IF EXISTS: A Clear Guide to Conditional Statements

SQLite Operators in Qlik Replicate

When using SQLite as a target in Qlik Replicate data replication, you can define filters and transformations using SQLite syntax:

WHERE $salary$ > 80000 AND $dept$ IS NOT NULL

This Record Selection Condition would filter rows during replication. SQLite’s operators like > and IS NOT NULL can be used this way.

Advanced SQLite Syntax

Beyond the basics, SQLite also includes more advanced database features:

Views

Views can be created to define a commonly used query as a virtual table:

CREATE VIEW viewname AS SELECT columns FROM table WHERE condition;

Triggers

Triggers execute custom logic before or after inserts, updates, and deletes:

CREATE TRIGGER name BEFORE INSERT ON table FOR EACH ROW BEGIN -- trigger logic END;

Data Types

SQLite has basic data types like INTEGER, TEXT, BLOB, REAL, and NUMERIC. It also supports custom types like datetimes by combining these primitives.

Character Sets

SQLite supports storing text in common character sets like UTF-8, UTF-16BE, and UTF-16LE. This is specified when creating the table schema.

This covers some more advanced functionality that SQLite makes available beyond just basic SQL syntax.

Frequently Asked Questions

Here are some common questions about SQLite syntax and capabilities:

Start Your SQLite Journey

SQLite provides a lightweight embedded database option by implementing a stripped-down but useful subset of SQL syntax. As we covered, it contains basic statements for creating tables, manipulating data, querying and filtering results, and handling advanced functionality like views and triggers. With its simple deployment and familiar interface, SQLite is an excellent choice for many applications.

For more details on SQLite syntax and capabilities, check the official SQLite documentation. If you have any other questions, feel free to reach out!