Enable multi-column user-defined aggregate functions

src/38query.js

@@ -123,10 +123,19 @@ function queryfn3(query) {
 		if (query.aggrKeys.length > 0) {
 			var gfns = '';
 			query.aggrKeys.forEach(function (col) {
+				// For multi-column aggregates, pass undefined for each column parameter
+				var undefinedArgs = '';
+				if (col.args && col.args.length > 1) {
+					// Multi-column: pass undefined for each argument, then accumulator, then stage
+					undefinedArgs = Array(col.args.length).fill('undefined').join(',') + ',';
+				} else {
+					// Single column: pass undefined, accumulator, stage
+					undefinedArgs = 'undefined,';
+				}
 				gfns += `
 				g[${JSON.stringify(col.nick)}] = alasql.aggr[${JSON.stringify(
 					col.funcid
-				)}](undefined,g[${JSON.stringify(col.nick)}],3); `;
+				)}](${undefinedArgs}g[${JSON.stringify(col.nick)}],3); `;
 			});
 			var gfn = new Function('g,params,alasql', 'var y;' + gfns);
 		}

src/423groupby.js

@@ -164,7 +164,15 @@ yy.Select.prototype.compileGroup = function (query) {
 					} else if (col.aggregatorid === 'REDUCE') {
 						query.aggrKeys.push(col);
 						const extraParams = getGroupConcatParams(col);
-						return `'${colas}':alasql.aggr['${col.funcid}'](${colexp},undefined,1${extraParams}),`;
+						// Support multiple arguments for user-defined aggregates
+						if (col.args && col.args.length > 1) {
+							// Multiple arguments - pass all of them
+							let argExpressions = col.args.map(arg => arg.toJS('p', tableid, defcols)).join(',');
+							return `'${colas}':alasql.aggr['${col.funcid}'](${argExpressions},undefined,1${extraParams}),`;
+						} else {
+							// Single argument - backward compatibility
+							return `'${colas}':alasql.aggr['${col.funcid}'](${colexp},undefined,1${extraParams}),`;
+						}
 					}
 					return '';
 				}
@@ -435,11 +443,20 @@ yy.Select.prototype.compileGroup = function (query) {
 							${post}`;
 					} else if (col.aggregatorid === 'REDUCE') {
 						const extraParams = getGroupConcatParams(col);
-						return `${pre}
-							g['${colas}'] = alasql.aggr.${col.funcid}(${colexp},g['${colas}'],2${extraParams});
-							${post}`;
+						// Support multiple arguments for user-defined aggregates
+						if (col.args && col.args.length > 1) {
+							// Multiple arguments - pass all of them
+							let argExpressions = col.args.map(arg => arg.toJS('p', tableid, defcols)).join(',');
+							return `${pre}
+								g['${colas}'] = alasql.aggr.${col.funcid}(${argExpressions},g['${colas}'],2${extraParams});
+								${post}`;
+						} else {
+							// Single argument - backward compatibility
+							return `${pre}
+								g['${colas}'] = alasql.aggr.${col.funcid}(${colexp},g['${colas}'],2${extraParams});
+								${post}`;
+						}
 					}
-
 					return '';
 				}
 

src/alasqlparser.jison

@@ -1462,6 +1462,7 @@ Aggregator
 	| AGGR { $$ = "AGGR"; }
 	| ARRAY { $$ = "ARRAY"; }
 	| GROUP_CONCAT { $$ = "GROUP_CONCAT"; }
+	| CORR { $$ = "CORR"; }
 /*	| REDUCE { $$ = "REDUCE"; } */
 	;
 
@@ -1474,7 +1475,7 @@ FuncValue
 					$$ = new yy.FuncValue({funcid: funcid, args: exprlist, over: $6});
 			} else if(alasql.aggr[$1]) {
 		    	$$ = new yy.AggrValue({aggregatorid: 'REDUCE',
-                      funcid: funcid, expression: exprlist.pop(),distinct:($3=='DISTINCT'), over: $6 });
+                      funcid: funcid, expression: exprlist[0], args: exprlist, distinct:($3=='DISTINCT'), over: $6 });
 		    } else {
 			    $$ = new yy.FuncValue({funcid: funcid, args: exprlist, over: $6});
 			};