insert row and get generated ID

问题:

I'm trying to use Spring's JdbcTemplate class to insert a row into a MySQL table named transaction and get the generated ID. The relevant code is:

public Transaction insertTransaction(final Transaction tran) {

    // Will hold the ID of the row created by the insert
    KeyHolder keyHolder = new GeneratedKeyHolder();

    getJdbcTemplate().update(new PreparedStatementCreator() {
        public PreparedStatement createPreparedStatement(Connection connection) throws SQLException {

            PreparedStatement ps = connection.prepareStatement(INSERT_TRAN_SQL);
            ps.setString(1, tran.getTransactionType().toString());

            Date sqlDate = new Date(tran.getDate().getTime());
            ps.setDate(2, sqlDate);
            ps.setString(3, tran.getDescription());

            return ps;
        }
    }, keyHolder);

    tran.setId(keyHolder.getKey().longValue());
    return tran;
}

But the following exception is thrown by the call to getJdbcTemplate().update

java.sql.SQLException: Generated keys not requested. You need to specify Statement.RETURN_GENERATED_KEYS to Statement.executeUpdate() or Connection.prepareStatement().

Can I insert the row and get the generated ID, without abandoning JdbcTemplate? I'm using Spring 2.5, MySQL 5.5.27 and MySQL Connector 5.1.26.

回答1:

Just prepare your Statement as follows

PreparedStatement ps = connection.prepareStatement(
                           INSERT_TRAN_SQL, Statement.RETURN_GENERATED_KEYS);

The underlying JDBC driver (used indirectly through the Spring's JdbcTemplate here) requires a hint that you would like to retrieve the generated keys. This can be done either while preparing a PreparedStatement as

connection.prepareStatement(strSQL, Statement.RETURN_GENERATED_KEYS);

or, at the time of executing a Statement as

statement.executeUpdate(strSQL, Statement.RETURN_GENERATED_KEYS);

This is what your java.sql.SQLException is pointing at as well.

回答2:

There is an easier way to get that behaviour:

protected JdbcTemplate            jdbcTemplate;
private SimpleJdbcInsert          insert;

    this.jdbcTemplate = new JdbcTemplate(this.databaseSetup.getDataSource());
    this.insert = new SimpleJdbcInsert(this.jdbcTemplate).withTableName(this.tableName).usingGeneratedKeyColumns(this.pkColumn);

Then you create a Map called parameters which conmtains the values for each column name in your table and insert a record like this:

    final Map<String, Object> parameters = new HashMap<>();
    parameters.put("empName", employee.getName()); // store the String name of employee in the column empName
    parameters.put("dept", employee.getDepartment()); // store the int (as Integer) of the employee in the column dept
    final Number key = this.insert.executeAndReturnKey(parameters);
    final long pk = key.longValue();

回答3:

You can retrieve the next sequence number like in step 1, then it can passed in the insert statement as in the step 2:

1-

Integer nextSeq = (Integer) getJdbcTemplate().queryForObject(
        "select SEQ_CUSTOMER_ID.nextVal from dual", new Object[] {}, Integer.class);

2-

getJdbcTemplate().update(
        "INSERT INTO customer "
        + "(CUST_ID, NAME, UPDATED) VALUES (?, ?, ?)",
        new Object[] { nextSeq ,customer.getName(),
                customer.getUpdated() });