查询在SQLDeveloper中有效，但在JDBC中无效

Question

I have the following query:

SELECT MAX(ID) FROM INGRESO_SALIDA_BUQUES WHERE ID_BUQUE = 1;

which works when I execute it in SQLDeveloper. It returns one row and just one column: the biggest ID where ID_BUQUE = 1.

Now, I'm using jdbc to connect to the database and do the same operation. Here is the code:

String sql = "SELECT MAX(ID) AS MAXIMO FROM INGRESO_SALIDA_BUQUES ";
    sql += "WHERE ID_BUQUE = " + registroSalida.getIdBuque();

PreparedStatement prepStmt = conn.prepareStatement(sql);
    recursos.add(prepStmt);
    ResultSet rs = prepStmt.executeQuery();

The las line of code is the one that throws the error.

The result from the eclipse console (For your reference "Nombre de columna no válido" means invalid column name):

18:40:27,712 ERROR [stderr] (default task-2) SQLException:Nombre de columna no válido
18:40:27,712 ERROR [stderr] (default task-2) java.sql.SQLException: Nombre de columna no válido
18:40:27,713 ERROR [stderr] (default task-2)    at oracle.jdbc.driver.OracleStatement.getColumnIndex(OracleStatement.java:3724)
18:40:27,713 ERROR [stderr] (default task-2)    at oracle.jdbc.driver.OracleResultSetImpl.findColumn(OracleResultSetImpl.java:2799)
18:40:27,713 ERROR [stderr] (default task-2)    at oracle.jdbc.driver.OracleResultSet.getString(OracleResultSet.java:498)

I tried deleting all rows except 1, in order to see hat would happen if I change MAX(ID) TO ID . This query works. I tried again MAX(ID) with just one row and it failed again.

The table has was created with this code:

CREATE TABLE INGRESO_SALIDA_BUQUES (
    ID NUMBER,
    ID_BUQUE NUMBER NOT NULL,
    FECHA_INGRESO DATE NOT NULL,
    FECHA_SALIDA DATE,
    CONSTRAINT PK_ISB PRIMARY KEY (ID),
    CONSTRAINT FK_ISB_ID_BUQUE FOREIGN KEY (ID_BUQUE) REFERENCES BUQUE(ID));

Do you know how to solve this?

recursos is just just an ArrayList:

private ArrayList<Object> recursos;

And in the constructor I initialize it. recursos = new ArrayList();

I use it to save the resources necesary to the SQL statement, in order to close them later.

The method to close them is this:

public void cerrarRecursos() {
    for(Object ob : recursos){
        if(ob instanceof PreparedStatement)
            try {
                ((PreparedStatement) ob).close();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
    }
}

Answer 1

The stack trace shows the error is coming from

oracle.jdbc.driver.OracleResultSet.getString(OracleResultSet.java:498)

... so it's being raised from an rs.getString() call, not the prepStmt.executeQuery() you think it's coming from.

Since you said it works if you change you query to get ID instead of MAX(ID) , code you haven't shown is doing rs.getString("ID") - otherwise it would still have failed after that change. If you use a column name in the getString then it has to match the column alias from the query.

You can either change your result set handling to do rs.getString("MAXIMO") to use the alias you've shown in your query, or rs.getString(1) to use positional notation; or change the query alias from MAXIMO to ID .