node js mysql Cannot Enqueue a query after calling quit

Question

I am using node.js and mysql, to run sql commands frequently.

I am getting this error: Cannot enqueue Handshake after invoking quit.

This is when I do

connection = mysql.createConnection(sqlDetails);
connection.connect();

and

connection.end();

If I comment the .connect and .end lines, then I get the error ER_CON_COUNT_ERROR: Too many connections.

Does anyone know how to fix this problem?

Thanks

have you seen this: http://stackoverflow.com/questions/14087924/cannot-enqueue-handshake-after-invoking-quit — knowbody, Apr 27 '14 at 20:34
According to this https://github.com/felixge/node-mysql#error-handling, it says to define your connection one, then just use that always. I did that, but now I'm not sure where to put my `connection.end()`. It says `You can listen on the error event to handle server disconnection and for reconnecting purposes.` but im not sure which function to put it in... — omega, Apr 27 '14 at 20:43
you should close one global connection the first request done, do not use a connection pool and grab a connection for each request separately or dont close the connection in the request handlers — knowbody, Apr 27 '14 at 20:48

score 2 · Answer 1 · answered Apr 28 '14 at 02:05

If you actually want to close connection (why? if you 'run sql commands frequently' you probably want to reuse it, or even better - use connection pool) you need to do that in query result callback. All commands are put into commands queue and processed sequentially.

This is what you are doing:

open connection stream to mysql
add Handshake command to queue
add Query command to queue
add Quit command to queue, mark connection as closing
start processing commands
now Handshake is processed when connection in 'closing' state

score 2 · Answer 2 · answered Oct 17 '14 at 12:24

Since node js is asynchronous , connection.connect() and connection.end() gets executed parallely,

If you want to specify sequence of execution, use callbacks like

connection = mysql.createConnection(sqlDetails);
connection.connect(function(err,callback){
    connection.query(function(err,callback){
         connection.end();
 });
});

node js mysql Cannot Enqueue a query after calling quit

2 Answers2