this.createCore = function (coreNumber) {
        var self = this;
        return connection.knex('core').insert({coreNumber: coreNumber})
            .then(function(data){
                return new Promise(function (resolve, reject) {
                        resolve(data[0]);
                })
        },
            function(err) {
                return self.getCoreId(coreNumber);
            })
    }