Value from last inserted row in DB [duplicate]
Is there some way to get a value from the last inserted row?
I am inserting a row where the PK will automatically increase due to sequence created, and I would like to get this sequence number. Only the PK is guaranteed to be unique in the table.
I am using Java with a JDBC and Oracle.
I forgot to add that I would like to retrieve this value using the resultset below. (I have tried this with mysql and it worked successfully, but I had to switch over to Oracle and now I get a string representation of the 开发者_如何学运维ID and not the actually sequence number)
Statement stmt = conn.createStatement();
stmt.executeUpdate(insertCmd, Statement.RETURN_GENERATED_KEYS);
stmt.RETURN_GENERATED_KEYS;
ResultSet rs = stmt.getGeneratedKeys();
if(rs.next()){
log.info("Successful insert");
id = rs.getString(1);
}
The above snippet would return the column int value stored in a mysql table. But since I have switched over to Oracle, the value returned is now a strange string value.
What you're trying to do is take advantage of the RETURNING
clause. Let's setup an example table and sequence:
CREATE TABLE "TEST"
( "ID" NUMBER NOT NULL ENABLE,
"NAME" VARCHAR2(100 CHAR) NOT NULL ENABLE,
CONSTRAINT "PK_TEST" PRIMARY KEY ("ID")
);
CREATE SEQUENCE SEQ_TEST;
Now, your Java code should look like this:
String insertSql = "BEGIN INSERT INTO TEST (ID, NAME) VALUES (SEQ_TEST.NEXTVAL(), ?) RETURNING ID INTO ?; END;";
java.sql.CallableStatement stmt = conn.prepareCall(insertSql);
stmt.setString(1, "John Smith");
stmt.registerOutParameter(2, java.sql.Types.VARCHAR);
stmt.execute();
int id = stmt.getInt(2);
This is not consistent with other databases but, when using Oracle, getGeneratedKeys()
returns the ROWID for the inserted row when using Statement.RETURN_GENERATEDKEYS
. So you need to use the oracle.sql.ROWID
proprietary type to "read" it:
Statement stmt = connection.createStatement();
stmt.executeUpdate(insertCmd, Statement.RETURN_GENERATED_KEYS);
ResultSet rs = stmt.getGeneratedKeys();
oracle.sql.ROWID rid = (oracle.sql.ROWID) rs.getObject(1);
But this won't give you the generated ID of the PK. When working with Oracle, you should either use the method executeUpdate(String sql, int[] columnIndexes)
or executeUpdate(String sql, String[] columnNames)
instead of executeUpdate(String sql, int autoGeneratedKeys)
to get the generated sequence value. Something like this (adapt the value to match the index or the name of your primary key column):
stmt.executeUpdate(INSERT_SQL, new int[] {1});
ResultSet rs = stmt.getGeneratedKeys();
Or
stmt.executeUpdate(INSERT_SQL, new String[] {"ID"});
ResultSet rs = stmt.getGeneratedKeys();
While digging a bit more on this, it appears that this approach is shown in the Spring documentation (as mentioned here) so, well, I guess it can't be totally wrong. But, unfortunately, it is not really portable and it may not work on other platforms.
You should use ResultSet#getLong()
instead. If in vain, try ResultSet#getRowId()
and eventually cast it to oracle.sql.ROWID
. If the returned hex string is actually the ID in hexadecimal flavor, then you can try converting it to decimal by Long#valueOf()
or Integer#valueOf()
.
Long id = Long.valueOf(hexId, 16);
That said, Oracle's JDBC driver didn't support ResultSet#getGeneratedKeys()
for a long time and is still somewhat troublesome with it. If you can't get that right, then you need to execute a SELECT CURRVAL(sequencename)
on the same statement as you did the insert
, or a new statement inside the same transaction, if it was a PreparedStatement
. Basic example:
public void create(User user) throws SQLException {
Connection connection = null;
PreparedStatement preparedStatement = null;
Statement statement = null;
ResultSet generatedKeys = null;
try {
connection = daoFactory.getConnection();
preparedStatement = connection.prepareStatement(SQL_INSERT);
preparedStatement.setValue(1, user.getName());
// Set more values here.
int affectedRows = preparedStatement.executeUpdate();
if (affectedRows == 0) {
throw new SQLException("Creating user failed, no rows affected.");
}
statement = connection.createStatement();
generatedKeys = statement.executeQuery(SQL_CURRVAL);
if (generatedKeys.next()) {
user.setId(generatedKeys.getLong(1));
} else {
throw new SQLException("Creating user failed, no generated key obtained.");
}
} finally {
close(generatedKeys);
close(statement);
close(preparedStatement);
close(connection);
}
}
Oh, from your code example, the following line
stmt.RETURN_GENERATED_KEYS;
is entirely superfluous. Remove it.
You can find here another example which I posted before about getting the generated keys, it uses the normal getGeneratedKeys()
approach.
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