On May 21, 2014, at 08:22, Janos wrote:
> is there anybody who can help me? I think I have a asynchronous data problem:
>
> My Code ( I made 3 approaches)
>
> var http = require('http');
> var work = require('timetrack');
> var mysql = require('mysql');
> var qs = require('querystring');
> var sync = require('synchronize')
>
> function getonevalue(statement) //approach1
[snip]
> function getonevalue3(statement) //approach2
[snip]
> function getonevalue2 (statement) //approach3
[snip]
> I called them via e.g.
>
> var myreturn = mysqlhandler.getonevalue3("Select username from tbluser where
> username = '" + username + "'");
> console.log('checkuser returnvalue:');
>
> console.log(myreturn);)
[snip]
> The only thing I want is a synchron function which delivers one value from a
> mysql db!
This can't work. The database returns the result asynchronously, so you cannot
write a function that interacts with it synchronously.
Your function signature needs to be:
function getonevalue(statement, callback)
And you will write that function to call the callback once it has gotten the
value from the database. So you will call it like this:
mysqlhandler.getonevalue("Select username from tbluser where username = '" +
username + "'", function(err, myreturn) {
if (err) {
console.error(err);
return;
}
console.log(myreturn));
});
And then there are other problems, such as you shouldn't be creating an SQL
string by concatenating user-supplied values such as username, but that's a
different topic.
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