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Databas supports three core SQL statements. Each statement has specific syntax requirements and capabilities.

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SELECT statement

The SELECT statement retrieves data from tables or evaluates expressions.

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Basic syntax

SELECT column1, column2, column3;
You can select expressions without a table: 
SELECT 1 + 2;
SELECT 'Hello, World!';
SELECT 3.14 * 2;

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FROM clause

Specify a table to query: 
SELECT id, name, email FROM users;
Databas only supports selecting from a single table. Joins are not supported.

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WHERE clause

Filter rows based on a condition: 
SELECT id, name FROM users WHERE age > 18;
SELECT * FROM products WHERE price <= 100.00;
SELECT name FROM customers WHERE active == true;
The WHERE clause accepts any valid expression that evaluates to a boolean.

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ORDER BY clause

Sort results by one or more expressions: 
-- Sort by single column ascending (default)
SELECT name, age FROM users ORDER BY age;

-- Sort descending
SELECT name, price FROM products ORDER BY price DESC;

-- Sort ascending (explicit)
SELECT name FROM users ORDER BY name ASC;

-- Sort by multiple columns
SELECT name, age FROM users ORDER BY age, name DESC;
When ordering by multiple columns, the ordering direction (ASC or DESC) applies to all columns in the list.

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LIMIT clause

Restrict the number of results: 
SELECT * FROM users LIMIT 10;
SELECT name FROM products ORDER BY price DESC LIMIT 5;
The LIMIT value must be a non-negative integer.

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OFFSET clause

Skip a number of rows before returning results: 
SELECT * FROM users OFFSET 10;
SELECT * FROM users LIMIT 10 OFFSET 20;
Combining LIMIT and OFFSET enables pagination: 
-- Page 1 (first 10 rows)
SELECT * FROM users LIMIT 10 OFFSET 0;

-- Page 2 (next 10 rows)
SELECT * FROM users LIMIT 10 OFFSET 10;

-- Page 3 (next 10 rows)
SELECT * FROM users LIMIT 10 OFFSET 20;

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Wildcard selector

Use * to select all columns: 
SELECT * FROM users;
SELECT * FROM products WHERE price > 50;

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Aggregate functions

Compute aggregate values:
Count the number of rows:
SELECT COUNT(*) FROM users;
SELECT COUNT(email) FROM users;
You can use multiple aggregate functions in one query: 
SELECT COUNT(*), SUM(price), AVG(price), STDDEV(price), MAX(price), MIN(price) FROM products;

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Complete SELECT example

Here’s a SELECT statement using all available clauses: 
SELECT foo FROM bar WHERE baz ORDER BY qux LIMIT 10 OFFSET 5;

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INSERT statement

The INSERT statement adds new rows to a table.

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Syntax

INSERT INTO table_name (column1, column2, column3) VALUES (value1, value2, value3);

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Single row insert

INSERT INTO users (id, name, age) VALUES (1, 'Alice', 30);
INSERT INTO products (id, name, price) VALUES (123, 'Laptop', 999.99);

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Multiple row insert

Insert multiple rows in a single statement: 
INSERT INTO products (id, name, price) 
VALUES 
  (123, 'Cake', 45.67), 
  (789, 'Waffles', 10.00);

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Data types in INSERT

You can insert different literal types: 
INSERT INTO users (id, age) VALUES (1, 25);

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Requirements

The INSERT statement requires:
  • The INTO keyword after INSERT
  • Column names enclosed in parentheses
  • The VALUES keyword
  • At least one set of values enclosed in parentheses
  • All statements must end with a semicolon

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CREATE TABLE statement

The CREATE TABLE statement defines a new table with columns and optional constraints.

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Basic syntax

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

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Data types

Databas supports three data types:
  • INT - 32-bit signed integer
  • FLOAT - 32-bit floating-point number
  • TEXT - String data

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Simple table

CREATE TABLE users (
  id INT,
  name TEXT,
  age INT
);

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Table with all types

CREATE TABLE products (
  id INT,
  name TEXT,
  price FLOAT
);

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Column constraints

You can add constraints to columns:

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PRIMARY KEY

Mark a column as the primary key: 
CREATE TABLE users (
  id INT PRIMARY KEY,
  name TEXT,
  age INT
);

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NULLABLE

Allow a column to contain null values: 
CREATE TABLE users (
  id INT,
  name TEXT NULLABLE,
  email TEXT NULLABLE
);
By default, columns are NOT NULL. You must explicitly mark columns as NULLABLE if you want to allow null values.

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Multiple constraints

You can combine constraints: 
CREATE TABLE users (
  id INT PRIMARY KEY,
  name TEXT,
  bio TEXT NULLABLE
);

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Requirements

The CREATE TABLE statement requires:
  • The TABLE keyword after CREATE
  • A valid table name (not a SQL keyword)
  • At least one column definition
  • Each column must have a name and type
  • Column definitions enclosed in parentheses
  • A semicolon at the end

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Reserved keywords

You cannot use SQL keywords as table names: 
-- This will fail:
CREATE TABLE table (id INT);

-- This will succeed:
CREATE TABLE users (id INT);

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Statement termination

All SQL statements must end with a semicolon: 
SELECT * FROM users;  -- Correct
SELECT * FROM users   -- Error: ExpectedCommaOrSemicolon

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Error examples

Here are common parsing errors: 
-- Missing expression after SELECT
SELECT;
-- Error: ExpectedExpression

-- Missing table name
CREATE TABLE (id INT);
-- Error: ExpectedIdentifier

-- Invalid data type
CREATE TABLE users (id VARCHAR);
-- Error: InvalidDataType

-- Negative LIMIT value
SELECT * FROM users LIMIT -1;
-- Error: ExpectedNonNegativeInteger

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