Question

我现在正在使用批处理：

String query = "INSERT INTO table (id, name, value) VALUES (?, ?, ?)";
PreparedStatement ps = connection.prepareStatement(query);            
for (Record record : records) {
    ps.setInt(1, record.id);
    ps.setString(2, record.name);
    ps.setInt(3, record.value);
    ps.addBatch();
}
ps.executeBatch();

我只是想知道上面的代码是否等同于以下代码。如果没有，哪个更快？

String query = "INSERT INTO table (id, name, value) VALUES ";
for (Record record : records) {
    query += "(" + record.id + ",'" + record.name + "'," + record.value + "),";
}
query = query.substring(1, query.length() - 1);
PreparedStatement ps = connection.prepareStatement(query);
ps.executeUpdate();

Answer 1

只要自动提交设置为false，

executeBatch的性能就会提高executeUpdate：

connection.setAutoCommit(false);  
PreparedStatement ps = connection.prepareStatement(query);            
for (Record record : records) {
    // etc.
    ps.addBatch();
}
ps.executeBatch();
connection.commit();

Answer 2

首先，使用查询字符串连接，您不仅会丢失PreparedStatement方法的原生类型转换，而且还容易受到在数据库中执行的恶意代码的攻击。</ p>

其次，PreparedStatements以前是在数据库本身中缓存的，这已经比普通语句提供了非常好的性能提升。

Answer 3

如果要插入的项目数量很大，则可能会遇到严重的性能问题。因此，更安全的方法是定义批处理大小，并在达到批处理大小时不断执行查询。

类似以下示例代码的东西应该可以工作。有关如何有效使用此代码的完整信息，请参阅此link。

private static void insertList2DB(List<String> list) {
        final int batchSize = 1000; //Batch size is important.
        Connection conn = getConnection();
        PreparedStatement ps = null;
        try {
            String sql = "INSERT INTO theTable (aColumn) VALUES (?)";
            ps = conn.prepareStatement(sql);

            int insertCount=0;
            for (String item : list) {
                ps.setString(1, item);
                ps.addBatch();
                if (++insertCount % batchSize == 0) {
                    ps.executeBatch();
                }
            }
            ps.executeBatch();

        } catch (SQLException e) {
            e.printStackTrace();
            System.exit(1);
        }
    finally {
        try {
            ps.close();
            conn.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

Answer 4

如果您的记录大小小于或等于 1000，则以下代码优于您的两个代码：

StringBuilder query = new StringBuilder("INSERT INTO table (id, name, value) VALUES ");

if (records.size() <= 1000) {
    
    for (int i = 0; i < records.size(); i++)
        query.append("(?, ?, ?), ");

    query = new StringBuilder(query.substring(1, query.length() - 1));

    PreparedStatement ps = connection.prepareStatement(query.toString());

    for (int i = 0; i < records.size(); i++) {
        ps.setInt((i * 3) + 1, record.id);
        ps.setString((i * 3) + 2, record.name);
        ps.setInt((i * 3) + 3, record.value);
    }
    
    ps.executeUpdate();
    
}

通过这种方式，您将使用 PreparedStatement 并根据记录列表的大小在一个插入查询中使用多个值子句动态创建它

Answer 5

public void insertBatch(final List<Record > records ) {

    String query = "INSERT INTO table (id, name, value) VALUES (?, ?, ?)";


    GenericDAO.getJdbcTemplate().batchUpdate(sql, new BatchPreparedStatementSetter() {


        @Override
        public void setValues(PreparedStatement ps, int i) throws SQLException {
              Record record = records .get(i);
              ps.setInt(1, record.id);
              ps.setString(2, record.name);
              ps.setInt(3, record.value);
        }

        @Override
        public int getBatchSize() {
            return records.size();
        }
    });
}

Answer 6

我认为这样做

String query = "INSERT INTO table (id, name, value) VALUES ";
for (Record record : records)
{
query += "(" + record.id + ",'" + record.name + "'," + record.value + "),";
query = query.substring(1, query.length() - 1);
PreparedStatement ps = connection.prepareStatement(query);
ps.executeUpdate();
}

因为您必须为每个要插入数据库的记录执行查询。

JDBC插入多行

6 个答案: