parseQueryString(query) {
        let queryString = '';
        if (query.select !== undefined) {
            queryString += "SELECT " + query.select;
        } else {
            if (this.selectable.length > 0) {
                let selectableColumns = this.selectable.join(', ');
                queryString += `SELECT ${selectableColumns}`;
            } else {
                queryString += "SELECT *";
            }
        }

        if (query.table === undefined)
            throw new SyntaxError("Undefined table name");
        else
            queryString += " FROM " + query.table;

        if (query.join !== undefined) {
            queryString += " " + query.join.type + " JOIN " + query.join.rightTable;
            queryString += " ON " + query.table + "." + query.join.leftField + " = " + query.join.rightTable + "." + query.join.rightField;
        }

        if (query.where !== undefined)
            queryString += " WHERE " + query.where;

        if (query.groupBy !== undefined)
            queryString += " GROUP BY " + query.groupBy;

        if (query.orderBy !== undefined)
            queryString += " ORDER BY " + query.orderBy;

        return queryString;
    }
/**
     * converting _query object into string select statement
     * @param {object} query 
     */
converting _query object into string select statement
@param {object} query
converting _query object into string select statement @param { object } query
parseQueryString(query) {
        let queryString = '';
        if (query.select !== undefined) {
            queryString += "SELECT " + query.select;
        } else {
            if (this.selectable.length > 0) {
                let selectableColumns = this.selectable.join(', ');
                queryString += `SELECT ${selectableColumns}`;
            } else {
                queryString += "SELECT *";
            }
        }
        if (query.table === undefined)
            throw new SyntaxError("Undefined table name");
        else
            queryString += " FROM " + query.table;
        if (query.join !== undefined) {
            queryString += " " + query.join.type + " JOIN " + query.join.rightTable;
            queryString += " ON " + query.table + "." + query.join.leftField + " = " + query.join.rightTable + "." + query.join.rightField;
        }
        if (query.where !== undefined)
            queryString += " WHERE " + query.where;
        if (query.groupBy !== undefined)
            queryString += " GROUP BY " + query.groupBy;
        if (query.orderBy !== undefined)
            queryString += " ORDER BY " + query.orderBy;
        return queryString;
    }
parseQueryString ( query ) { let queryString = '' ; if ( query . select !== undefined ) { queryString += "SELECT " + query . select ; } else { if ( this . selectable . length > 0 ) { let selectableColumns = this . selectable . join ( ', ' ) ; queryString += ` ${ selectableColumns } ` ; } else { queryString += "SELECT *" ; } } if ( query . table === undefined ) throw new SyntaxError ( "Undefined table name" ) ; else queryString += " FROM " + query . table ; if ( query . join !== undefined ) { queryString += " " + query . join . type + " JOIN " + query . join . rightTable ; queryString += " ON " + query . table + "." + query . join . leftField + " = " + query . join . rightTable + "." + query . join . rightField ; } if ( query . where !== undefined ) queryString += " WHERE " + query . where ; if ( query . groupBy !== undefined ) queryString += " GROUP BY " + query . groupBy ; if ( query . orderBy !== undefined ) queryString += " ORDER BY " + query . orderBy ; return queryString ; }
converting _query object into string select statement
 @param {object} query
converting _query object into string select statement @param { object } query