const users = [{UserId: '1', UserName: 'User'}] const orders = [{UserId: '1', Text: 'Order text'}] const expected = alasql(` SELECT * FROM ? u JOIN ? o ON u.UserId = o.UserId`, [users, orders]) const unexpected = alasql(` SELECT UserName,Text FROM ? u JOIN ? o ON u.UserId = o.UserId`, [users, orders]) console.log({expected, unexpected}); // { // expected: [{ // Text: "Order text", <- "Text" field is there ... // UserId: "1", // UserName: "User" // }], // unexpected: [{ // Text: undefined, <- ... but it is undefined when selected // UserName: "User" // }] // }