public class Main {
    public static void main(String[] args) {
        String[] fields = {"name", "position", "salary"};
        String table = "employee";
        String select = buildSelectSql(table, fields);
        System.out.println(select);
        System.out.println("SELECT name, position, salary FROM employee".equals(select) ? "测试成功" : "测试失败");
    }

    static String buildSelectSql(String table, String[] fields) {
        StringJoiner sql = new StringJoiner(", ", "SELECT ", " FROM ");
        for (String field: fields) {
            sql.add(field);
        }
        return  sql + table;
    }
}