MySQL placeholders throw error on WHERE clause - mysql

Question

I am using MySQL placeholders and create promise to use them with async await.
selectTickets: (variable) => {
const sqlStatement = `SELECT * FROM tickets WHERE userID = ?`;
return new Promise((resolve, reject) => {
db.query(sqlStatement, variable, (error, response) => {
if (error) return reject(error);
return resolve(response);
});
});
},
i tried even to create the statement with interpolation and gave me an error:
"Unknown column 'undefined' in 'where clause'"
This is my code. But when I am using it in react, I am getting Error 500 status saying that the statement is incorrect.
ode: 'ER_PARSE_ERROR',
errno: 1064,
sqlMessage: "You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '?' at line 1",
sqlState: '42000',
index: 0,
sql: 'SELECT * FROM tickets WHERE userID = ?'
I tried alot of other methods. But other functions that uses same type of function with same type of statement are working just fine.
In react I have this call:
const URL_TICKETS_BY_USERID = 'http://localhost:3000/api/get-tickets';
const config = {
headers: { Authorization: `Bearer ${user.token}` }
};
const userID = user.userID;
axios.get(URL_TICKETS_BY_USERID,
userID,
config
)
.then(data => console.log(data))
.catch(error => console.log(error))
Can i have some help?

Answer 1

The problem lies with your db.query() call. The second parameter should be an array, even for single values. This should work:
db.query(sqlStatement, [variable], (error, response) => {
if (error) return reject(error);
return resolve(response);
});
Also axios get() takes two parameters: url and config (optional). This means that any params should be part of that config object:
const config = {
headers: { Authorization: `Bearer ${user.token}` },
params: {
id: user.userID
}
};
axios.get(URL_TICKETS_BY_USERID, config)
Alternatively pass it as a GET parameter in the URL:
axios.get(URL_TICKETS_BY_USERID + "?id=" + user.userID, config)

Answer 2

In my case it was the question mark. In some database systems, the question mark is used as a placeholder for values that are passed in separately. However, it seems that in my case, the database system is not recognizing the question mark as a placeholder, and is interpreting it as part of the query.
So changed the query to:-
const q = `SELECT * FROM list WHERE userid = ${listId}`;
I passed the variable inside the query and it works now