我在 mysql 中有很多项目，我正在计算平均和第一个产品的平均值影响所有产品，

ResultSet rs = localStat.executeQuery("SELECT * FROM (SELECT * FROM tablename ORDER BY id DESC) AS data GROUP BY productname ");
      
while (rs.next()) {
    String str4 = rs.getString("productname ");
    int i = rs.getInt("Tradata");
    int t = rs.getInt("tra_tot");
         
    ResultSet rs1 = localStat2.executeQuery("SELECT productname,avg(Tradata) as average FROM (SELECT * FROM tablename ORDER BY id DESC) AS data GROUP BY productname");

    while (rs1.next()) {
        j = rs1.getInt("average"); 
    }
           
    int k = 1;
    if (i < j) {
        k = j - i;       
    }

    ResultSet rs3 = localStatement2.executeQuery("SELECT * FROM (SELECT * FROM talename ORDER BY id DESC) AS data GROUP BY productname  ");
    int m = 1;
    int n = 0;
    int i1 = 0;
    while (rs3.next()) {
        n += 1;
    }

    rs3 = localStatement2.executeQuery("SELECT * FROM (SELECT * FROM talename ORDER BY id DESC) AS data GROUP BY productname ");
       
    while (rs3.next()) {
        if (m == n / 2) {
            i1 = rs3.getInt("Tradata");
        }

        if (m == n / 2 + 1) {
            i1 = i1 + rs3.getInt("Tradata");
        }
        m += 1;  
    }
       
    k = i1 - i;
      
    if (i < i1) {
        System.out.println(localSimpleDateFormat.format(data) + "data decreasing "+((k * 100) / i1) + "%  (" + k + ") average(" + i1 + ") in " + str4);
    }
}

这段代码的输出是：

data decreasing 99%  (303) average(305)
data decreasing 91%  (278) average(305) 
data decreasing 8%  (27) average(305) 
data decreasing 100%  (305) average(305) 
data decreasing 100%  (305) average(305) 

请有人帮助我。