Question

我正在尝试使用ionic.app.scss获取此查询SELECT mac, stop_name from behaviour where mac = ?的受影响记录的数量。如何获取受影响的行数？

代码：

executeQuery

Answer 1

这是一个读取操作，因此不会影响任何行。如果您想获得返回的行数，那么您可以执行以下操作之一

使用计数器变量并在循环while (rsBehav.next())

使用可滚动的结果集

PreparedStatement prepared = con.prepareStatement(
        "SELECT mac, stop_name from behaviour where mac = ?",
        ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
ResultSet rsBehav = prepared.executeQuery();
rsBehav.afterLast();
int numRow = rsBehav.getRow();
rsBehav.beforeFirst();

这里numRow会给你返回的数字或行，

Answer 2

if (behaviourExist.next()) {
PreparedStatement prepared = con
        .prepareStatement("SELECT mac, stop_name from behaviour where mac = ?");
prepared.setString(1, macD);
ResultSet rsBehav = prepared.executeQuery();
ArrayList<String> stopNameList = new ArrayList<String>();
int numberOfRows = 0;
while (rsBehav.next()) {
    ++numberOfRows;
    String stNa = rsBehav.getString("stop_name");
    if (stNa.equals(nameShortestDistance)) {
        stopNameList.add(stNa);

    }
}
}

这里变量numberOfRows将在每次循环运行时递增，这将为您提供resultSet中的总行数。

Answer 3

PreparedStatement prepared = con
        .prepareStatement(
         "SELECT (SELECT count(*) from where mac = ?),"
         " mac, stop_name from behaviour where mac = ?");
prepared.setString(1, macD);
prepared.setString(2, macD);
ResultSet rsBehav = prepared.executeQuery();
ArrayList<String> stopNameList = new ArrayList<String>();
while (rsBehav.next()) {
    int numberOfRows = rsBehav.getInt(1);
    String stNa = rsBehav.getString("stop_name");
    // ....

获取受影响的行数

3 个答案: