Strange SQLException: Column not found

问题

I'm getting a weird SQLException on a function I run against a database using JDBC. SQLException: Column 'Message' not found.

I have this in my function:

    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();

And I got that error, so I added this after the st.executeQuery() :

    ResultSetMetaData meta = rs.getMetaData();
    for (int index = 1; index <= meta.getColumnCount(); index++) {
        System.out.println("Column " + index + " is named " + meta.getColumnName(index));
        }

And when I run my code again this is what I get as a result:

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

I really can't figure out what's going one here.... Anyone can help out?

EDIT
I've replaced the * in the SELECT statement just to add something to the question that I just noticed.
If I remove the Message column from the select then I get the same error for the TimeStamp column. And if I remove both columns I get no errors then.

EDIT2
OK,this is the part i get the errors, i get both on Message and Timestamp:

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();
        }
    }

I get the error on the getString() methods for each column
StackTrace for TimeStamp(the same for 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)

回答1:

If you observe your code

try {
        time = rs.getString("Timestamp");
        System.out.println("time: " + time);
    } catch (Exception e) {
        System.out.println("Timestamp error: " + e);
        e.printStackTrace();
    }
}

you have used "Timestamp" in this format but if you changed it to "TimeStamp" as specified in your database, hopefully it will work.

回答2:

Change datatype of your isNotified column as TINYINT in database and retry to insert

isNotified TINYINT(1)

Bool, Boolean: These types are synonyms for TINYINT(1). A value of zero is considered false. Non-zero values are considered true.

回答3:

Can you change

System.out.println("Column " + index + " is named " + meta.getColumnName(index));

System.out.println("Column " + index + " is named '" + meta.getColumnName(index) + "'");

so that we can see if there is whitespace in the "Message" column name?

The fact that the error message comes between column 5 and 6 is not important I think, because one is Standard Output and the other one Standard Error, these are not synchronized output streams.

(Also see the previous answer about Timestamp vs TimeStamp.)

回答4:

It sounds like the table metadata is corrupt. You should be able to correct this by dropping and recreating the table, although if the metadata is really borked you may not be able to drop the table. If that's the case or you need to keep the data, backing up and restoring the whole database is the way to go, but check the SQL dump file before restoring and/or restore to another database name before dropping the broken database. Depending on exactly what's wrong, your problem columns may be missing from the dump.

If refreshing the database is not an option there are ways to perform targetted repairs, but I'm no expert so I can't advise you on that. Again, back up your database AND verify that the backup is complete (i.e. it has all your columns) before proceeding. If this is a production database, I would be very wary about taking advice from the internet on manipulating metadata. Minor differences in version, storage engine and environment can make or break you with this stuff, and given the nature of the problem you can't do a dry run.

来源：https://stackoverflow.com/questions/19672412/strange-sqlexception-column-not-found

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java

mysql

sqlexception