java JDBC：查明查询是否成功？
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JDBC: Find out if query was successful?
提问by user1795609
I'm using JDBC with mysql. I can get my queries to work great. But for update queries for instance I was wondering if there was any way to determine whether the update was successful for for example if the row could not be found.
我在 mysql 中使用 JDBC。我可以让我的查询工作得很好。但是对于例如更新查询，我想知道是否有任何方法可以确定更新是否成功，例如如果找不到该行。
UPDATE TABLE SET column = 'newvalue' WHERE primary_key =2
I would like to get the specific error message if possible, this way I can throw a specific exception as to why the query failed.
如果可能的话，我想获取特定的错误消息，这样我就可以抛出一个特定的异常，说明查询失败的原因。
Thanks for your help.
谢谢你的帮助。
回答by a_horse_with_no_name
executeUpdate() will return the number of rows that were affected by your SQL statement:
executeUpdate() 将返回受 SQL 语句影响的行数：
int rows = stmt.executeUpdate("UPDATE ...");
System.out.println(rows + " rows updated");
Of course you could have found out yourself by simply looking at the JavaDocs:
当然，您可以通过简单地查看 JavaDocs 来发现自己：
Returns: either (1) the row count for SQL Data Manipulation Language (DML) statements or (2) 0 for SQL statements that return nothing
返回： (1) SQL 数据操作语言 (DML) 语句的行数或 (2) 0 不返回任何内容的 SQL 语句
回答by Reimeus
executeUpdatereturns the row count of rows affected. You could use this to check that your update was executed successfully:
executeUpdate返回受影响行的行数。您可以使用它来检查您的更新是否成功执行：
PreparedStatement pstmt = con.prepareStatement("UPDATE TABLE ...");
int rowsUpdated = pstmt.executeUpdate();
if (rowsUpdated == 0) {
// handle no update
}
