Java jdbc 批量仅插入新行

Question

如何使用 jdbc 仅针对新行(目标表中不存在 ID 列值)高效地执行向 Sql Server 表的批量插入？

实际上我正在使用PreparedStatement对象来创建批处理，但没有“仅在新行时插入”逻辑:

String sqlInsertStub = "INSERT INTO mytable (id, col2, col3) values (?, ?, ?)";

try (PreparedStatement preparedStatement = connection.prepareStatement(sqlInsertStub)) {

    connection.setAutoCommit(false);

    int processed = 0;

    while (resultSet.next()) {

        // [...]

        preparedStatement.setInt(1, id);
        preparedStatement.setString(2, col2);
        preparedStatement.setString(3, col3);

        preparedStatement.addBatch();

        if (++processed % BATCH_SIZE == 0) {
            preparedStatement.executeBatch();
            connection.commit();
        }

    }

    preparedStatement.executeBatch();
    connection.commit();    


catch (Exception e) {

    connection.rollBack();
    e.printStackTrace();
    System.exit(1);

}

Answer 1

一种选择是在表中的三列上添加唯一约束，以确定唯一性。然后，尝试插入重复记录应该会导致 Java 异常。但是，这可能会导致整个批处理失败。如果您想要其他选项，可以将查询更改为以下内容:

INSERT INTO mytable
SELECT ?, ?, ?
WHERE NOT EXISTS (SELECT 1 FROM mytable
                  WHERE id = ? AND col2 = ? AND col3 = ?);

对于此查询，您将值绑定(bind)两次，如下所示:

preparedStatement.setInt(1, id);
preparedStatement.setString(2, col2);
preparedStatement.setString(3, col3);
preparedStatement.setInt(4, id);
preparedStatement.setString(5, col2);
preparedStatement.setString(6, col3);