因此，您可以使用类似select count(*) ...或select (count(*) > 0) as found ...作为基本查询的内容。
当您致电时executeQuery，您将得到一个ResultSet回报，您需要确定它的内容。
在您的情况下，您只期望得到单行结果，因此您可以简单地使用ResultSet#next移动到第一行，然后从中提取列值…
public void ftpTableCheck(String host, String port, String username, String password) {
try {
String query = "SELECT (count(*) > 0) as found FROM ftp WHERE Host LIKE ? AND Username LIKE ?";
PreparedStatement pst = conn.prepareStatement(query);
pst.setString(1, host);
pst.setString(2, username);
try (ResultSet rs = pst.executeQuery()) {
// Only expecting a single result
if (rs.next()) {
boolean found = rs.getBoolean(1); // "found" column
if (found) {
// You have rows
} else {
// You have no rows
}
}
}
} catch (sqlException e) {
e.printStackTrace();
}
}
602392714
清零编程群