Nodejs delete from table but select not working - mysql

Question

user_id=3;
//Delete from table query working perfect
db.query("DELETE FROM table WHERE user_id=" + user_id, function(dberr,dbres){
addUserInventories(detail, req, function(err,invres){
getHomePageDataWithInvntory(req, function(request, response){
callback(null, response);
});
});
});
//Here add record in table
function addUserInventories(detail, req, callback){
//After insertion called following and working perfect
return callback(null, null);
});
//Here retrieve record from table but not getting result after delete and insert operation
function getHomePageDataWithInvntory(req, callback){
user_id=3;
db.query("SELECT * FROM table WHERE user_id=" + user_id, function(err, results){
callback(null, results); //Here result getting empty array
});
});
In above code Delete record and Insert record work perfect but Retrieving record is not working.
Note : There is no any syntax error in SQL Query and In log file it print SELECT * FROM table WHERE user_id=3

Answer 1

When I got this kind of error, I always save them with the same process :
console.log your query string before using it
Use a database client like Sequel Pro, MySQL Workbench for sql
Copy paste your query manually in the client and run it
Generally, you'll get a syntax error, just solve it in the database client and your solution should work
Database client is not mandatory as you can run the query with command line, but the client will be a simpler interface for you and is more likely to give you more details on your syntax error.
Can you try this process ? If you don't succeed in solving the syntax error in the database client, you can put the query here so we can help you
Just in case : with your example, I'll use this pattern to log the query if you have trouble to do it, this give you an idea of how to do it in your code
//Here retrieve record from table but not getting result after delete and insert operation
function getHomePageDataWithInvntory(req, callback){
user_id=3;
var queryString = "SELECT * FROM table WHERE user_id=" + user_id;
console.log(queryString);
db.query(queryString, function(err, results){
callback(null, results); //Here result getting empty array
});
});