java JDBC插入多行

Question

我现在使用的是批处理：

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下面的代码。如果不是，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

如果您的记录大小小于或等于1000，则以下代码优于这两种代码：

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();
    
}

这样，您就可以使用PreparedStatement，并在一个insert查询中使用多个values子句根据记录列表的大小动态创建它

Answer 2

首先，使用查询字符串连接，不仅会丢失PreparedStatement方法本机的类型转换，而且还容易受到数据库中执行的恶意代码的攻击

第二，PreparedStatements以前缓存在数据库本身中，这已经比普通语句有了很好的性能改进

Answer 3

我想这个就行了

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();
}

因为您必须对每个要插入数据库的记录执行查询

Answer 4

关闭自动提交

只要将autocommit设置为false，那么executeBatch将比executeUpdate具有更好的性能：

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

Answer 5

如果要插入的项目数量很大，则可能会面临严重的性能问题。因此，更安全的做法是定义批量大小，并在达到批量大小时持续执行查询

下面的示例代码应该可以使用。有关如何有效地使用此代码的完整故事，请参见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 6

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();
        }
    });
}