Add FORMAT function for numeric formatting with thousands separators

src/55functions.js

@@ -500,3 +500,17 @@ stdfn.NEWID =
 				lut[(d3 >> 24) & 0xff]
 			);
 		};
+
+/**
+ * FORMAT(value, decimals[, locale])
+ * MySQL-style: formats number with comma thousands separators and decimal places
+ */
+stdfn.FORMAT = function (value, decimals, locale) {
+	if (value == null) return null;
+	var num = Number(value);
+	if (isNaN(num)) return null;
+	var [integerPart, decimalPart] = Math.abs(num).toFixed(decimals).split('.');
+	var formatted = integerPart.replace(/\B(?=(\d{3})+(?!\d))/g, ',');
+	if (decimals > 0) formatted += '.' + decimalPart;
+	return (num < 0 ? '-' : '') + formatted;
+};

test/test105-B.js

@@ -0,0 +1,100 @@
+if (typeof exports === 'object') {
+	var assert = require('assert');
+	var alasql = require('..');
+}
+
+describe('Test 105-B - FORMAT function', function () {
+	const test = '105B';
+
+	before(function () {
+		alasql('create database test' + test);
+		alasql('use test' + test);
+	});
+
+	after(function () {
+		alasql('drop database test' + test);
+	});
+
+	it('A) MySQL-style numeric formatting - FORMAT(number, decimals)', function () {
+		// Basic number formatting with 2 decimal places
+		var res = alasql('SELECT VALUE FORMAT(12332.123456, 2)');
+		assert.equal(res, '12,332.12');
+
+		// Single decimal place
+		res = alasql('SELECT VALUE FORMAT(12332.2, 1)');
+		assert.equal(res, '12,332.2');
+
+		// No decimal places
+		res = alasql('SELECT VALUE FORMAT(12332.2, 0)');
+		assert.equal(res, '12,332');
+
+		// Small number
+		res = alasql('SELECT VALUE FORMAT(123.456, 2)');
+		assert.equal(res, '123.46');
+	});
+
+	it('B) FORMAT with negative numbers', function () {
+		var res = alasql('SELECT VALUE FORMAT(-12332.123456, 2)');
+		assert.equal(res, '-12,332.12');
+
+		res = alasql('SELECT VALUE FORMAT(-999.99, 0)');
+		assert.equal(res, '-1,000');
+	});
+
+	it('C) FORMAT with zero and NULL', function () {
+		var res = alasql('SELECT VALUE FORMAT(0, 2)');
+		assert.equal(res, '0.00');
+
+		res = alasql('SELECT VALUE FORMAT(NULL, 2)');
+		assert.equal(res, null);
+	});
+
+	it('D) FORMAT in table queries', function () {
+		alasql('CREATE TABLE prices (id INT, price DECIMAL(10,2))');
+		alasql('INSERT INTO prices VALUES (1, 1234.567), (2, 98765.4321), (3, 0.99)');
+
+		var res = alasql('SELECT id, FORMAT(price, 2) AS formatted FROM prices ORDER BY id');
+		assert.deepEqual(res, [
+			{id: 1, formatted: '1,234.57'},
+			{id: 2, formatted: '98,765.43'},
+			{id: 3, formatted: '0.99'},
+		]);
+
+		alasql('DROP TABLE prices');
+	});
+
+	it('E) FORMAT with different decimal precision', function () {
+		var res = alasql('SELECT VALUE FORMAT(1234.56789, 0)');
+		assert.equal(res, '1,235');
+
+		res = alasql('SELECT VALUE FORMAT(1234.56789, 1)');
+		assert.equal(res, '1,234.6');
+
+		res = alasql('SELECT VALUE FORMAT(1234.56789, 3)');
+		assert.equal(res, '1,234.568');
+
+		res = alasql('SELECT VALUE FORMAT(1234.56789, 4)');
+		assert.equal(res, '1,234.5679');
+	});
+
+	it('F) FORMAT with very large numbers', function () {
+		var res = alasql('SELECT VALUE FORMAT(1234567890.123, 2)');
+		assert.equal(res, '1,234,567,890.12');
+
+		res = alasql('SELECT VALUE FORMAT(999999999999.99, 2)');
+		assert.equal(res, '999,999,999,999.99');
+	});
+
+	it('G) FORMAT with numbers less than 1', function () {
+		var res = alasql('SELECT VALUE FORMAT(0.123456, 2)');
+		assert.equal(res, '0.12');
+
+		res = alasql('SELECT VALUE FORMAT(0.999, 0)');
+		assert.equal(res, '1');
+	});
+
+	it('H) FORMAT with string numbers', function () {
+		var res = alasql("SELECT VALUE FORMAT('1234.567', 2)");
+		assert.equal(res, '1,234.57');
+	});
+});