mysql - 我想计算 mysql 中的列并将结果放在文本字段中

Question

我有一个 mysql 数据库，其中有一个名为 MemType 的列，该列将显示成员是否处于事件状态。并非所有成员都活跃。我想计算活跃成员的数量并将结果显示在文本字段中。我可以计算，但不知道结果如何返回。我的代码如下:

@FXML
private void CountActionPerformed(ActionEvent event) { 
    String user = "root";
    String password = "";

    String ResultSet = null; // This is to ensure that ResultSet is empty.

    try {
        Connection myConn = DriverManager.getConnection("jdbc:mysql://localhost:3306/club", user, password);
        System.out.println("Connection Successful ");

        // Create statement.
        Statement myStmt = myConn.createStatement();      

        ResultSet myRs = myStmt.executeQuery("SELECT COUNT(MemType)\n "
            + "FROM members \n "
            + "WHERE  MemType = 'Active ' ");

        while (myRs.next()) {
            CountRel.setText(myRs.getString("MemType"));
        }
    } catch (Exception  e) {
    }
}

Answer 1

您可以为该列指定一个别名，如下所示:

ResultSet myRs = myStmt.executeQuery("SELECT COUNT(MemType) as MemType "
        + "FROM members "
        + "WHERE  MemType = 'Active ' ");

这应该是您需要的所有更改，并且您只会得到一个结果(所有事件行的计数)