Let GROUP BY support table-prefixed columns in arithmetic expressions to fix #536 (#2297)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: mathiasrw <1063454+mathiasrw@users.noreply.github.com>

Author: Copilot

src/50expression.js

@@ -734,7 +734,11 @@
 			}
 
 			if (context === 'g') {
-				return `g['${this.nick}']`;
+				// When accessing grouped columns, use columnid (without table prefix) if nick is not set
+				// This handles cases like: SELECT a.id + 1 FROM ... GROUP BY a.id
+				// where the column in the expression doesn't have nick set, but the group stores it by columnid
+				const nickToUse = this.nick || this.columnid;
+				return `g['${nickToUse}']`;
 			}
 
 			if (this.tableid) {

test/test536-B.js

@@ -0,0 +1,78 @@
+if (typeof exports === 'object') {
+	var assert = require('assert');
+	var alasql = require('..');
+}
+
+describe('Test 536 - GROUP BY on field of type INTEGER with table prefix', function () {
+	const test = '536B';
+
+	before(function () {
+		alasql('create database test' + test);
+		alasql('use test' + test);
+	});
+
+	after(function () {
+		alasql('drop database test' + test);
+	});
+
+	it('A) Simple GROUP BY with arithmetic on INTEGER field (baseline)', function () {
+		alasql('create table data( id INTEGER PRIMARY KEY, grp INTEGER)');
+		alasql('insert into data select range._ as id , range._ % 3 as grp  from RANGE(0,9)as range');
+
+		var res = alasql('select id, id +1 as id_plus_1 from data group by id');
+
+		// Check that the arithmetic operation works correctly
+		assert.strictEqual(res.length, 10);
+		assert.strictEqual(res[0].id, 0);
+		assert.strictEqual(res[0].id_plus_1, 1);
+		assert.strictEqual(res[1].id, 1);
+		assert.strictEqual(res[1].id_plus_1, 2);
+		assert.strictEqual(res[9].id, 9);
+		assert.strictEqual(res[9].id_plus_1, 10);
+	});
+
+	it('B) GROUP BY with table prefix in SELECT arithmetic operations', function () {
+		alasql('create table data2( id INTEGER PRIMARY KEY, grp INTEGER)');
+		alasql('insert into data2 select range._ as id , range._ % 3 as grp  from RANGE(0,9)as range');
+
+		// This is the failing case from the issue
+		var res = alasql(
+			'select a.id, a.id +1 as id_plus_1, CAST(a.id AS INTEGER) +1 as cast_plus_1 ' +
+				'from data2 as a, data2 as b ' +
+				'where a.id < b.id and a.grp = b.grp ' +
+				'group by a.id'
+		);
+
+		// Should have 7 rows (0,1,2,3,4,5,6 have matching pairs)
+		assert.strictEqual(res.length, 7);
+
+		// Check first row
+		assert.strictEqual(res[0].id, 0);
+		assert.strictEqual(res[0].id_plus_1, 1, 'a.id + 1 should equal 1 for id=0');
+		assert.strictEqual(res[0].cast_plus_1, 1, 'CAST(a.id AS INTEGER) + 1 should equal 1 for id=0');
+
+		// Check another row
+		assert.strictEqual(res[2].id, 2);
+		assert.strictEqual(res[2].id_plus_1, 3, 'a.id + 1 should equal 3 for id=2');
+		assert.strictEqual(res[2].cast_plus_1, 3, 'CAST(a.id AS INTEGER) + 1 should equal 3 for id=2');
+	});
+
+	it('C) GROUP BY with table prefix - without table prefix in expressions (workaround)', function () {
+		alasql('create table data3( id INTEGER PRIMARY KEY, grp INTEGER)');
+		alasql('insert into data3 select range._ as id , range._ % 3 as grp  from RANGE(0,9)as range');
+
+		// The workaround mentioned in the issue - use column names without table prefix in expressions
+		var res = alasql(
+			'select a.id, (id +1) as id_plus_1, CAST(id AS INTEGER) +1 as cast_plus_1 ' +
+				'from data3 as a, data3 as b ' +
+				'where a.id < b.id and a.grp = b.grp ' +
+				'group by a.id'
+		);
+
+		// Should work correctly
+		assert.strictEqual(res.length, 7);
+		assert.strictEqual(res[0].id, 0);
+		assert.strictEqual(res[0].id_plus_1, 1);
+		assert.strictEqual(res[0].cast_plus_1, 1);
+	});
+});