JDBC PreparedStatement-是否可以使用相同的参数? [英] JDBC PreparedStatement - Using the same argument, is it possible?

问题描述

我正在使用插入或更新"查询，例如以下查询:

I'm using an "insert or update" query such as the one below:

        String sql = 
            "INSERT INTO servlets (path, applicationId, startTime, numOfRequests, totalResponseTime, totalBytes)" +
            "VALUES (?, ?, NOW(), 1, ?, ?)" +
            "ON DUPLICATE KEY UPDATE numOfRequests = numOfRequests + 1, " +
            "totalResponseTime = totalResponseTime + ?, totalBytes = totalBytes + ?";

我正在使用准备好的语句，并通过以下方式用相关的参数填充它:

I'm using prepared statements and fill it with the relevant arguments in the following manner:

        statement = connection.prepareStatement(sql);
        statement.setString(1, i_ServletModel.GetPath());
        statement.setInt(2, i_ServletModel.GetApplicationId());
        statement.setLong(3, i_RequestStats.GetResponseTime());
        statement.setLong(4, i_RequestStats.GetBytes());
        statement.setLong(5, i_RequestStats.GetResponseTime());
        statement.setLong(6, i_RequestStats.GetBytes());

请注意，参数3与参数5完全相同，参数4与参数6完全相同，因为它们在上面的查询中需要相同的值.

Notice that argument 3 is exactly the same as argument 5 and argument 4 is exactly the same as argument 6 since they require the same value in the query above.

在查询或自变量填充方法中，有什么我可以更改的方法，以避免这种丑陋"的语法吗?

Is there anything I can change, either in the query or in the arguments filling methods to avoid such an "ugly" syntax?

推荐答案

使用局部变量，可以减少代码的丑陋程度和出错率.但是JDBC不支持命名参数的缺点仍然存在.同一参数将再次出现多行.

Using a local variable, you can make the code less ugly and error-prone. But the shortcoming of JDBC that it does not support named parameters still holds. There will be again multiple lines for the same parameter.

    statement = connection.prepareStatement(sql);

    long time = i_RequestStats.GetResponseTime();
    long bytes = i_RequestStats.GetBytes();

    statement.setString(1, i_ServletModel.GetPath());
    statement.setInt(2, i_ServletModel.GetApplicationId());
    statement.setLong(3,time);
    statement.setLong(4, bytes);
    statement.setLong(5, time);
    statement.setLong(6, bytes);

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