node-mysql multiple statements in one query

Question

I'm using nodejs 10.26 + express 3.5 + node-mysql 2.1.1 + MySQL-Server Version: 5.6.16.

I got 4 DELETE's and want only 1 Database Request, so i connected the DELETE commands with a ";"... but it fails always.

var sql_string = "DELETE FROM user_tables WHERE name = 'Testbase';";
sql_string += "DELETE FROM user_tables_structure WHERE parent_table_name = 'Testbase';";
sql_string += "DELETE FROM user_tables_rules WHERE parent_table_name = 'Testbase';";
sql_string += "DELETE FROM user_tables_columns WHERE parent_table_name = 'Testbase';";

connection.query(sql_string, function(err, rows, fields) {
   if (err) throw err;
   res.send('true');
});

It throws this error:

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 'DELETE FROM user_tables_structure WHERE parent_table_name = 'Testbase';DELETE FR' at line 1

But if i paste this SQL in PhpMyAdmin it is always successful...

If i write it in single query's its succeed, too.

        connection.query("DELETE FROM user_tables WHERE name = 'Testbase'", function(err, rows, fields) {
        if (err) throw err;

        connection.query("DELETE FROM user_tables_structure WHERE parent_table_name = 'Testbase'", function(err, rows, fields) {
            if (err) throw err;


            connection.query("DELETE FROM user_tables_rules WHERE parent_table_name = 'Testbase'", function(err, rows, fields) {
                if (err) throw err;

                connection.query("DELETE FROM user_tables_columns WHERE parent_table_name = 'Testbase'", function(err, rows, fields) {
                    if (err) throw err;

                    res.send('true');
                });
            });
        });
    });

Thanks for help!

Answer 1

I guess you are using node-mysql. (but should also work for node-mysql2)

The docs says:

Support for multiple statements is disabled for security reasons (it allows for SQL injection attacks if values are not properly escaped).

Multiple statement queries

To use this feature you have to enable it for your connection:

var connection = mysql.createConnection({multipleStatements: true});

Once enabled, you can execute queries with multiple statements by separating each statement with a semi-colon ;. Result will be an array for each statement.

Example

connection.query('SELECT ?; SELECT ?', [1, 2], function(err, results) {
  if (err) throw err;

  // `results` is an array with one element for every statement in the query:
  console.log(results[0]); // [{1: 1}]
  console.log(results[1]); // [{2: 2}]
});

So if you have enabled the multipleStatements, your first code should work.

Answer 2

Using "multiplestatements: true" like shown below worked for me

var connection = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: '',
    database: '',
    multipleStatements: true
});
connection.connect();
 
var sql = "CREATE TABLE test(id INT DEFAULT 1, name VARCHAR(50));ALTER TABLE test ADD age VARCHAR(10);";
 
connection.query(sql, function(error, results, fields) {
    if (error) {
        throw error;
    }
});

Answer 3

To Fetch Data from DB(SQL), the following function would work accurately

router.get('/', function messageFunction(req, res){ //res.send('Hi Dear Rasikh, Welcome to Test Page.') //=> One Way dbConn.query('SELECT COUNT(name) as counted, name, last_name, phone, email from students', function (err, rows, fields) { // another Way if (err) throw err

  dbConn.query('SELECT name, author from books',
  function (err, rowsBook, fields) { // another Way
      if (err) throw err
    // console.log('The counted is: ', rows[0].counted);    //=> Display in console
    // res.send('Hi Dear Rasikh, Welcome to Test Page.'+ rows[0].counted)  //=> Display in blank page
    
    res.render('main/index',{data:rows, myData:rowsBook});
  })

}); });

Answer 4

This worked for me in Next.js...

export default async function handler(req, res) {
  try {
    // Build your multiple MySQL queries here
    const querySql = "DELETE FROM favorites WHERE user = ? AND listingID= ?";
    const querySql2 = "UPDATE properties SET saves = ? WHERE listingid = ?";

    // Pass any params here
    const valuesParams = [user, listingID];
    const valuesParams2 = [upDateSaves, listingID];

    //Execute your multiple MySQL queries here
    const data = await query({query: querySql, values: valuesParams });
    const data2 = await query({query: querySql2, values: valuesParams2 });

    //Combine the results
    const combinedResults = [data, data2];

    res.status(200).json({ 
    text: combinedResults,
   });

  } catch (error) {
    res.status(500).json({ error: 'Error fetching data' });
  }
}