NodeJS MYSQL delete query

Question

I am trying to delete a row in MYSQL table from NodeJS route. The query works fine by itself when i run it in MySQL Workbench. When executed from Node the row is not deleted. I don't get any error messages on either server or client side. Here is the code:

router.post('/bid_delete', async (req, res) => {
 let bid_no = req.body['bid_no']
 let qrBids= "SET SQL_SAFE_UPDATES = 0; DELETE FROM bids_hdr WHERE 
 bid_gen_id ='" + bid_no + "';"  
 await pool.query( qrBids, (err, result) => {
  if (err) {
    res.send(err)
  } else {
    res.json({success : true})
  }  
 });  
})

Thanks in advance for any guidance.

You can't execute multiple queries in a single call to pool.query(). Execute them sequentially. — Barmar
– Barmar, Commented Jun 19, 2019 at 15:52
You should also use placeholders in the query rather than concatenating strings, to prevent SQL injection. — Barmar
– Barmar, Commented Jun 19, 2019 at 15:52
@Barmar. Thank You very much. Can you explain briefly use of placeholders with example if possible. — goryef
– goryef, Commented Jun 19, 2019 at 15:54
Do you really have a newline in the qrBids string? JavaScript doesn't allow newlines in string literals (you can use them in template literals, but not single-quoted or double-quoted literals). — Barmar
– Barmar, Commented Jun 19, 2019 at 15:56

Barmar · Accepted Answer · 2019-06-19 15:55:26Z

1

Do SET SQL_SAFE_UPDTES = 0; in a separate query.

And use a placeholder instead of concatenation to substitute a variable into the query.

router.post('/bid_delete', async (req, res) => {
 let bid_no = req.body['bid_no']
 let qrBids= "DELETE FROM bids_hdr WHERE bid_gen_id = ?"  
 await pool.query( "SET SQL_SAFE_UPDATES = 0");
 await pool.query( qrBids, [bid_no], (err, result) => {
  if (err) {
    res.send(err)
  } else {
    res.json({success : true})
  }  
 });  
})

answered Jun 19, 2019 at 15:55

Barmar

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1 Comment

goryef Over a year ago

Got it. Thanks a lot.

Majid Mushtaq · Accepted Answer · 2019-06-19 15:54:44Z

0

Try to pass param as is eg.

let qrBids= "SET SQL_SAFE_UPDATES = 0; DELETE FROM bids_hdr WHERE bid_gen_id = '1';"

answered Jun 19, 2019 at 15:54

Majid Mushtaq

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1 Comment

Barmar Over a year ago

The parameter comes from a variable, he can't hard-code it like this.

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