loopback custom query did not give response

my loopback custom query cannot give response after some time. below is my code.

var ds = tbljourney.dataSource;
        ds.connector.query("select * from user where  email='" + data.email + "'"
        , function (err, user) {
                user = user[0];

            console.log("user", user);
            if (err) {
                console.log(err);

            }
            else if (user) { 
   }
  });

some time it give a response but after 50 or 60 attemps its stuck

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