Statement batch update

最新推荐文章于 2024-09-08 10:37:23 发布

转载最新推荐文章于 2024-09-08 10:37:23 发布 · 218 阅读

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原文链接：http://www.cnblogs.com/jcleung/archive/2009/04/30/1446906.html

本文介绍了如何在Java JDBC中通过关闭自动提交功能来实现数据库的批量更新操作，并使用事务确保数据的一致性和完整性。文中提供了具体的代码示例，展示了如何创建Statement对象、添加SQL语句到批处理中并执行批处理。

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To perform a Statement batch update, you must turn off auto-commit. In Java^(TM) Database Connectivity (JDBC), auto-commit is on by default. Auto-commit means any updates to the database are committed after each SQL statement is processed. If you want to treat a group of statements being handed to the database as one functional group, you do not want the database committing each statement individually. If you do not turn off auto-commit and a statement in the middle of the batch fails, you cannot roll back the entire batch and try it again because half of the statements have been made final. Further, the additional work of committing each statement in a batch creates a lot of overhead. See Transactions for more details.

After turning off auto-commit, you can create a standard Statement object. Instead of processing statements with methods such as executeUpdate, you add them to the batch with the addBatch method. Once you have added all the statements you want to the batch, you can process all of them with the executeBatch method. You can empty the batch at anytime with the clearBatch method.

The following example shows how you can use these methods:

Example: Statement batch update

Note: Read the Code example disclaimer for important legal information.

Code
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connection.setAutoCommit(false);
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Statement statement = connection.createStatement();
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statement.addBatch("INSERT INTO TABLEX VALUES(1, 'Cujo')");
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statement.addBatch("INSERT INTO TABLEX VALUES(2, 'Fred')");
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statement.addBatch("INSERT INTO TABLEX VALUES(3, 'Mark')");
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int [] counts = statement.executeBatch();
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connection.commit();

In this example, an array of integers is returned from the executeBatch method. This array has one integer value for each statement that is processed in the batch. If values are being inserted into the database, the value for each statement is 1 (that is, assuming successful processing). However, some of the statements may be update statements that affect multiple rows. If you put any statements in the batch other than INSERT, UPDATE, or DELETE, an exception occurs.

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转载于:https://www.cnblogs.com/jcleung/archive/2009/04/30/1446906.html