How do I post data from form to a particular row? - mysql

Question

My nodejs code...
app.post('/src/grades-form', function(req, res){
var daa = req.body.daa;
var os = req.body.os;
var dldm = req.body.dldm;
var ptrp = req.body.ptrp;
var bhr = req.body.bhr;
var prn = req.query.prn;
var sql = "INSERT INTO grades (daa, os, dldm, ptrp, bhr) VALUES ('"+daa+"','"+ os+"','"+ dldm+"','"+ ptrp+"','"+ bhr+"') WHERE prn = ?";
connection.query(sql, [prn], function(error, results){
if(error) throw error;
res.send(`Data stored successfully !!<br>Return to dashboard.`);
});
});
Error I'm getting...
Error: ER_PARSE_ERROR: You have an error in your SQL syntax; check the manual that corresponds to your MySQL
server version for the right syntax to use near 'WHERE prn = '1'' at line 1
How do I overcome it?
I will provide more info if this isn't sufficient... Thank you

Answer 1

What you could do is perform a SELECT to check if the row is present in the database, if so perform an update, otherwise insert a new row:
app.post('/src/grades-form', function (req, res) {
const { daa, os, dldm, ptrp, bhr } = req.body;
var prn = req.query.prn;
const sqlSelect = 'SELECT * FROM grades WHERE prn = ?';
connection.query(sqlSelect, [prn], (err, result) => {
if (err) throw err;
if (result.length === 0) {
// Not found, insert new value
var sqlInsert =
'INSERT INTO grades (daa, os, dldm, ptrp, bhr) VALUES (?, ?, ?, ?, ?)';
connection.query(
sqlInsert,
[daa, os, dldm, ptrp, bhr],
function (error, results) {
if (error) throw error;
res.send(
`Data inserted successfully !!<br>Return to dashboard.`
);
}
);
} else {
// Value is present, update existing one
var sqlUpdate =
'UPDATE grades SET daa = ?, os = ?, dldm = ?, ptrp = ?, bhr = ? WHERE prn = ?';
connection.query(
sqlUpdate,
[daa, os, dldm, ptrp, bhr, prn],
function (error, results) {
if (error) throw error;
res.send(
`Data updated successfully !!<br>Return to dashboard.`
);
}
);
}
});
});

Answer 2

The INSERT INTO statement cannot have a WHERE clause.
If you're trying to update an existing row, use:
UPDATE grades SET daa=value, os=value, etc=value WHERE prn = 1