Let SELECT * INTO SQL() handle NULL values to fix #42 (#2196)

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: mathiasrw <[email protected]>
Co-authored-by: Mathias Wulff <[email protected]>

Author: Copilot

src/830into.js

@@ -36,25 +36,28 @@ alasql.into.SQL = function (filename, opts, data, columns, cb) {
 			})
 			.join(',');
 		s += ') VALUES (';
-		s += columns.map(function (col) {
-			var val = data[i][col.columnid];
-			if (col.typeid) {
-				if (
-					col.typeid === 'STRING' ||
-					col.typeid === 'VARCHAR' ||
-					col.typeid === 'NVARCHAR' ||
-					col.typeid === 'CHAR' ||
-					col.typeid === 'NCHAR'
-				) {
-					val = "'" + escapeqq(val) + "'";
+		s += columns
+			.map(function (col) {
+				var val = data[i][col.columnid];
+				// Handle null and undefined values
+				if (val === null || val === undefined) {
+					return 'NULL';
 				}
-			} else {
-				if (typeof val == 'string') {
+				// Check if value should be escaped as a string
+				var shouldEscape =
+					(col.typeid &&
+						(col.typeid === 'STRING' ||
+							col.typeid === 'VARCHAR' ||
+							col.typeid === 'NVARCHAR' ||
+							col.typeid === 'CHAR' ||
+							col.typeid === 'NCHAR')) ||
+					typeof val == 'string';
+				if (shouldEscape) {
 					val = "'" + escapeqq(val) + "'";
 				}
-			}
-			return val;
-		});
+				return val;
+			})
+			.join(',');
 		s += ');\n';
 	}
 	//	if(filename === '') {

test/test42.js

@@ -0,0 +1,45 @@
+if (typeof exports === 'object') {
+	var assert = require('assert');
+	var alasql = require('..');
+}
+
+describe('Test 42 - NULL values in INTO SQL()', function () {
+	it('1. Should output NULL for null values', () => {
+		var data = [
+			{a: 1, b: 'test', c: null, d: 3},
+			{a: 2, b: null, c: 4, d: null},
+			{a: null, b: 'value', c: null, d: null},
+		];
+		var res = alasql('SELECT * INTO SQL({tableid:"test_table"}) FROM ?', [data]);
+
+		var expected =
+			"INSERT INTO test_table(a,b,c,d) VALUES (1,'test',NULL,3);\n" +
+			'INSERT INTO test_table(a,b,c,d) VALUES (2,NULL,4,NULL);\n' +
+			"INSERT INTO test_table(a,b,c,d) VALUES (NULL,'value',NULL,NULL);\n";
+
+		assert.deepEqual(res, expected);
+	});
+
+	it('2. Should handle undefined values as NULL', () => {
+		var data = [
+			{a: 1, b: 'test'},
+			{a: 2, b: undefined, c: 4},
+		];
+		var res = alasql('SELECT * INTO SQL({tableid:"test_table"}) FROM ?', [data]);
+
+		var expected =
+			"INSERT INTO test_table(a,b) VALUES (1,'test');\n" +
+			'INSERT INTO test_table(a,b) VALUES (2,NULL);\n';
+
+		assert.deepEqual(res, expected);
+	});
+
+	it('3. Should handle mixed NULL, undefined, and empty strings', () => {
+		var data = [{a: 1, b: '', c: null, d: undefined}];
+		var res = alasql('SELECT * INTO SQL({tableid:"test_table"}) FROM ?', [data]);
+
+		var expected = "INSERT INTO test_table(a,b,c,d) VALUES (1,'',NULL,NULL);\n";
+
+		assert.deepEqual(res, expected);
+	});
+});