Operators and Expressions

Stoolap supports a comprehensive set of SQL operators for building expressions in SELECT, WHERE, HAVING, and other clauses.

Comparison Operators

Operator	Description	Example
`=`	Equal	`WHERE id = 5`
`<>` or `!=`	Not equal	`WHERE status <> 'deleted'`
`<`	Less than	`WHERE price < 100`
`<=`	Less than or equal	`WHERE age <= 65`
`>`	Greater than	`WHERE score > 90`
`>=`	Greater than or equal	`WHERE date >= '2024-01-01'`

Logical Operators

Operator	Description	Example
`AND`	Both conditions true	`WHERE a > 1 AND b < 10`
`OR`	Either condition true	`WHERE status = 'active' OR status = 'pending'`
`NOT`	Negates a condition	`WHERE NOT deleted`

Arithmetic Operators

Operator	Description	Example
`+`	Addition	`SELECT price + tax`
`-`	Subtraction	`SELECT total - discount`
`*`	Multiplication	`SELECT quantity * price`
`/`	Division	`SELECT total / count`
`%`	Modulo (remainder)	`SELECT id % 10`

Bitwise Operators

Operator	Description	Example
`&`	Bitwise AND	`SELECT flags & 0x0F`
`\\|`	Bitwise OR	`SELECT flags \\| 0x10`
`^`	Bitwise XOR	`SELECT a ^ b`
`~`	Bitwise NOT	`SELECT ~flags`
`<<`	Left shift	`SELECT 1 << 4` (returns 16)
`>>`	Right shift	`SELECT 16 >> 2` (returns 4)

String Operators

Concatenation

-- Using || operator
SELECT first_name || ' ' || last_name AS full_name FROM users;

-- Using CONCAT function
SELECT CONCAT(first_name, ' ', last_name) AS full_name FROM users;

Pattern Matching

LIKE (Case-Sensitive)

-- % matches any sequence of characters
SELECT * FROM products WHERE name LIKE 'Apple%';      -- Starts with 'Apple'
SELECT * FROM products WHERE name LIKE '%Phone';      -- Ends with 'Phone'
SELECT * FROM products WHERE name LIKE '%Pro%';       -- Contains 'Pro'

-- _ matches any single character
SELECT * FROM products WHERE code LIKE 'A_C';         -- Matches 'ABC', 'A1C', etc.

ILIKE (Case-Insensitive)

-- Same as LIKE but ignores case
SELECT * FROM products WHERE name ILIKE 'apple%';     -- Matches 'Apple', 'APPLE', 'apple'
SELECT * FROM users WHERE email ILIKE '%@gmail.com';

GLOB (Shell-Style Patterns)

-- * matches any sequence of characters (like % in LIKE)
SELECT * FROM files WHERE name GLOB '*.txt';

-- ? matches any single character (like _ in LIKE)
SELECT * FROM files WHERE name GLOB 'file?.dat';

-- [...] matches any character in the set
SELECT * FROM files WHERE name GLOB '[abc]*';

REGEXP (Regular Expressions)

-- Full regex pattern matching
SELECT * FROM logs WHERE message REGEXP 'error|warning';
SELECT * FROM users WHERE email REGEXP '^[a-z]+@[a-z]+\.[a-z]+$';
SELECT * FROM data WHERE value REGEXP '[0-9]{3}-[0-9]{4}';

Range Operators

BETWEEN

-- Inclusive range check
SELECT * FROM products WHERE price BETWEEN 10 AND 100;

-- Equivalent to:
SELECT * FROM products WHERE price >= 10 AND price <= 100;

-- Works with dates
SELECT * FROM orders WHERE order_date BETWEEN '2024-01-01' AND '2024-12-31';

-- NOT BETWEEN
SELECT * FROM products WHERE price NOT BETWEEN 10 AND 100;

IN

-- Check if value is in a list
SELECT * FROM products WHERE category IN ('Electronics', 'Computers', 'Phones');

-- With numbers
SELECT * FROM orders WHERE status_id IN (1, 2, 3);

-- NOT IN
SELECT * FROM products WHERE category NOT IN ('Discontinued', 'Archived');

-- With subquery
SELECT * FROM customers WHERE id IN (SELECT customer_id FROM orders WHERE total > 1000);

NULL Operators

-- Check for NULL
SELECT * FROM users WHERE deleted_at IS NULL;

-- Check for NOT NULL
SELECT * FROM users WHERE email IS NOT NULL;

-- Note: = and <> don't work with NULL
SELECT * FROM users WHERE value = NULL;    -- Always returns no rows!
SELECT * FROM users WHERE value IS NULL;   -- Correct way

CASE Expression

-- Simple CASE
SELECT name,
    CASE status
        WHEN 'A' THEN 'Active'
        WHEN 'I' THEN 'Inactive'
        WHEN 'P' THEN 'Pending'
        ELSE 'Unknown'
    END AS status_name
FROM users;

-- Searched CASE
SELECT name, salary,
    CASE
        WHEN salary >= 100000 THEN 'Executive'
        WHEN salary >= 70000 THEN 'Senior'
        WHEN salary >= 40000 THEN 'Mid-level'
        ELSE 'Entry-level'
    END AS level
FROM employees;

Operator Precedence

From highest to lowest:

() - Parentheses
~ - Bitwise NOT
*, /, % - Multiplication, division, modulo
+, - - Addition, subtraction
<<, >> - Bit shifts
& - Bitwise AND
^ - Bitwise XOR
| - Bitwise OR
=, <>, <, <=, >, >= - Comparisons
NOT - Logical NOT
AND - Logical AND
OR - Logical OR

Use parentheses to control evaluation order:

-- Without parentheses: AND has higher precedence than OR
SELECT * FROM products WHERE category = 'A' OR category = 'B' AND price > 100;
-- Equivalent to: category = 'A' OR (category = 'B' AND price > 100)

-- With parentheses: explicit grouping
SELECT * FROM products WHERE (category = 'A' OR category = 'B') AND price > 100;

Examples

Complex WHERE Clauses

SELECT * FROM orders
WHERE status IN ('pending', 'processing')
  AND total BETWEEN 100 AND 1000
  AND customer_name ILIKE '%smith%'
  AND created_at >= DATE_SUB(NOW(), 30, 'day');

Computed Columns

SELECT
    product_name,
    quantity,
    unit_price,
    quantity * unit_price AS line_total,
    CASE WHEN quantity >= 10 THEN 0.1 ELSE 0 END AS discount_rate,
    quantity * unit_price * (1 - CASE WHEN quantity >= 10 THEN 0.1 ELSE 0 END) AS final_price
FROM order_items;

Bitwise Flags

-- Check if specific bit is set
SELECT * FROM permissions WHERE (flags & 0x04) = 0x04;  -- Check bit 2

-- Set a bit
UPDATE permissions SET flags = flags | 0x04 WHERE user_id = 1;

-- Clear a bit
UPDATE permissions SET flags = flags & ~0x04 WHERE user_id = 1;