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我正在使用登录表单。这段代码是从数据库中检查日志的详细信息。我能够在提供正确的用户名和密码时登录,但显示一个例外。我的代码如下:为什么“不能为SELECT发出executeUpdate()”SQLException显示?
public void signin() throws ClassNotFoundException, SQLException
{
try {
Class.forName("com.mysql.jdbc.Driver");
connect2 = DriverManager
.getConnection("jdbc:mysql://localhost:3306/mysql?"
+ "user=root&password=virus");
statement2 = connect2.createStatement();
preparedStatement2 = connect2
.prepareStatement("select username,password from "+t11.getText()+";");
resultSet2 = preparedStatement2.executeQuery();
writeResultSet(resultSet2);
preparedStatement2.executeUpdate();
}
catch (ClassNotFoundException | SQLException e) {
throw e;
} finally {
close1();
}
}
private void writeResultSet(ResultSet resultSet) throws SQLException {
while (resultSet.next()) {
String username = resultSet.getString("username");
String password = resultSet.getString("password");
String usr = (String)t11.getText();
String pwd = (String)pw11.getText();
if(t11.getText().equals(username) && pwd.equals(password))
{
((Stage)b1.getScene().getWindow()).setScene(new Scene(new UserPage()));
}
else
{
//...THIS IS WHERE I WANT TO DISPLAY THE ALERT BOX
}
}
}
private void close1() {
try {
if (resultSet2 != null) {
resultSet2.close();
}
if (statement != null) {
statement.close();
}
if (connect != null) {
connect.close();
}
} catch (SQLException e) {
}
}
唯一的例外是:
java.sql.SQLException: Can not issue executeUpdate() for SELECTs
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:988)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:974)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2416)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2375)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2359)
at login.Login.signin(Login.java:159)
at login.Login$1.handle(Login.java:118)
at login.Login$1.handle(Login.java:113)
为什么出此异常?我该如何纠正它?
@jewelsea如果我上面提到的查询工作正常,那么prepareStatement2和resultSet2的值是什么? – TomJ
这是一个完全不同的问题TomJ,请不要在评论中提出新问题。结果集应该包含查询结果(在这种情况下,用户名和密码)。您可以阅读[基本JDBC教程](http://docs.oracle.com/javase/tutorial/jdbc/basics/retrieving.html)以进一步了解结果集。 – jewelsea
@jewelsea还行。谢谢。 – TomJ