Question

*我在其他功能中没有得到max的值。值返回为“0”。我尝试但没有成功:( Image

public int PriceMax(int manhom){
        Connection conn = this.connect();
        int max = 0;
        if(conn != null){
            try {
                java.sql.Statement statement = conn.createStatement();
                String sql = "SELECT AVG(GiaSP) from tbsanpham where manhom = '"+manhom+"'";
                ResultSet rs = statement.executeQuery(sql);
                max = rs.getInt(sql);
            } catch (SQLException ex) {
                Logger.getLogger(CSDL.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
        return max;
    }

帮助!!!

int manhom = cbbNhomSanPham.getSelectedIndex();
        CSDL csdl = new CSDL();
        int max = csdl.PriceMax(manhom);
        JOptionPane.showMessageDialog(null, "Nhóm sản phẩm: '"+cbbNhomSanPham.getName()+"' \nPrice max: '"+max+"' ");

Answer 1

你没有按原样使用它。

首先，您使用ÀVG但需要MAX，因此请将其更改为MAX(GiaSP)。其次，您必须使用rs.next()让光标转到第一行，然后从中获取信息。

java.sql.Statement statement = conn.createStatement();
String sql = "SELECT MAX(GiaSP) from tbsanpham where manhom = '"+manhom+"'";
ResultSet rs = statement.executeQuery(sql);
if (rs.next()) {
    max = rs.getInt(1);
}

Answer 2

ResultSet rs = stmt.executeQuery("select MAX(GiaSP) as maxGiaSP from tbsanpham where manhom = '"+manhom+"'");
if (rs.next())
{
    int w = rs.getInt("maxGiaSP ");

    // just return this int
}

在Java中获取最大值sql

2 个答案: