sql jdbc getgeneratedkeys returns column “id” not found, column type unknown

Question

I want to retrieve the most recently updated value in the table using an insert query.

these are the datatypes in my sql table.

Datatype:

int(11)      // primary key auto increment, not being assigned by sqlQuery
varchar(30)
timestamp    // has a default value. but i am explicit assigning it using CURRENT_TIMESTAMP
varchar(300)
varchar(300)
varchar(300)
int(11)
varchar(300)

java code

   statement.executeUpdate(sqlQuery, Statement.RETURN_GENERATED_KEYS);
   ResultSet rs = statement.getGeneratedKeys();
   System.out.println("here: " + rs.getMetaData().getColumnCount());
   System.out.println("here1: " + rs.getMetaData().getColumnName(1));
   // none of the following 3 works
   System.out.println("id: " + rs.getInt(1));
   System.out.println("id: " + rs.getInt("GENERATED_KEY"));
   System.out.println("id: " + rs.getInt("id"));
   for a bit of background see [this][1]
  `rs.getMetaData().getColumnTypeName(1)` tells me column type `UNKNOWN`

stack trace

    SEVERE: null
    java.sql.SQLException
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1055)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)
    at com.mysql.jdbc.ResultSetImpl.checkRowPos(ResultSetImpl.java:815)
    at com.mysql.jdbc.ResultSetImpl.getStringInternal(ResultSetImpl.java:5528)
    at com.mysql.jdbc.ResultSetImpl.getString(ResultSetImpl.java:5448)
  [1]: http://stackoverflow.com/questions/2853066/sql-java-get-value-assigned-to-auto-increment-primary-key

Answer 1

You need to call rs.next() :

int autoIncKeyFromApi = -1;
rs = stmt.getGeneratedKeys();
if (rs.next()) {
    autoIncKeyFromApi = rs.getInt(1);
} else {
    // do what you have to do
}
System.out.println(autoIncKeyFromApi);

Answer 2

Maybe it's because that the sqlQuery doesn't create any new record! In this case, it will return an empty ResultSet Look at the specification of getGeneratedKeys()