我在使用 JDBC 对数据库运行的函数上遇到了奇怪的 SQLException。
SQLException:未找到列“消息”。
我的函数中有这个:
st = con.prepareStatement("SELECT NotificationID,UserIDFrom,UserIDTo,Message,Timestamp,isNotified FROM notification WHERE UserIDTo=? AND isNotified=?");
st.setInt(1, _UserID);
st.setBoolean(2, false);
System.out.println("st is: " + st);
rs = st.executeQuery();
我收到了这个错误,所以我在之后添加了这个st.executeQuery()
:
ResultSetMetaData meta = rs.getMetaData();
for (int index = 1; index <= meta.getColumnCount(); index++) {
System.out.println("Column " + index + " is named " + meta.getColumnName(index));
}
当我再次运行我的代码时,这就是我得到的结果:
Column 1 is named NotificationID
Column 2 is named UserIDFrom
Column 3 is named UserIDTo
Column 4 is named Message
Column 5 is named TimeStamp
Exception in thread "main" java.sql.SQLException: Column 'Message' not found.
Column 6 is named isNotified
And here is a screenshot of my table's design, from MySQL Workbench
And the data in the table
我真的不明白这里发生了什么......任何人都可以帮忙吗?
EDIT
我已经更换了*
in the SELECT
声明只是为了向我刚刚注意到的问题添加一些内容。
如果我删除Message
从选择列然后我得到相同的错误TimeStamp
柱子。如果我删除这两列,那么就不会出现错误。
EDIT2
好的,这是我收到错误的部分,我在消息和时间戳上都收到错误:
while (rs.next()) {
NotificationID = rs.getInt("NotificationID");
System.out.println("NotificationID: " + NotificationID);
SenderID = rs.getInt("UserIDFrom");
System.out.println("SenderID: " + SenderID);
From = findUserName(SenderID);
try {
body = rs.getString("Message");
System.out.println("body: " + body);
} catch (Exception e) {
System.out.println("Message error: " + e);
e.printStackTrace();
}
try {
time = rs.getString("Timestamp");
System.out.println("time: " + time);
} catch (Exception e) {
System.out.println("Timestamp error: " + e);
e.printStackTrace();
}
}
我收到错误getString()
每列的方法
堆栈跟踪TimeStamp
(同样对于Message
):
java.sql.SQLException: Column 'TimeStamp' not found.
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1078)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:989)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:975)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:920)
at com.mysql.jdbc.ResultSetImpl.findColumn(ResultSetImpl.java:1167)
at com.mysql.jdbc.ResultSetImpl.getString(ResultSetImpl.java:5733)
at NotifyMe_Server.Database.getUnNotified(Database.java:444)
at tests.Tests.main(Tests.java:39)