在Java中使用不必要的值执行了两次查询(错误) [英] Query executed twice (by error) in Java with unwanted values
问题描述
我正在使用JFreeChart在Java和MySQL中创建图表.
I'm using JFreeChart to create a chart in Java and MySQL.
当我尝试将值插入到另一个表中时，查询似乎被执行了两次，因为我多次获得相同的时间戳记...
When I try to insert my values in another table the query seems to be executed twice since I end up with the same timestamps multiple times...
这是我的代码的一部分:
Here's a part of my code :
private JDBCXYDataset createDataset() {
try {
Connection conn = DriverManager.getConnection(
"jdbc:mysql://localhost:bd?serverTimezone=UTC","MySQL", "MySQL");
conn.setAutoCommit(false);
SQLException savedException = null;
Statement st = conn.createStatement();
st.execute("DROP TABLE IF EXISTS test ");
st.execute("create table test(Table timestamp, Table float,Table float)");
String Date_Debut = "2020-06-25 00:00:00";
String Date_Fin = "2020-06-26 00:00:00";
String sql1 = "INSERT INTO test (Table ,Table ,Table ) "
+ "SELECT Table ,Table ,Table "
+ "FROM Table "
+ "WHERE Table BETWEEN ? AND ? ";
try ( PreparedStatement ps = conn.prepareStatement(sql1)){
ps.setString(1,Date_Debut);
ps.setString(2, Date_Fin);
ps.executeUpdate();
ps.close();
JDBCXYDataset jds = new JDBCXYDataset(conn);
st.close();
jds.executeQuery("SELECT Table ,Table ,Table FROM test");
conn.commit();
return jds;
} catch (SQLException ex) {
savedException = ex;
conn.rollback();
} finally {
conn.setAutoCommit(true);
if(savedException != null) {
throw savedException;
}
}
} catch (SQLException ex1) {
}
return null;
}
实际上，从数据库直接发出错误消息，主持人可以根据需要删除此帖子.但是，我让Trashgod的回复得到了验证，因为它的帮助不止于此. 对于可能遇到类似问题的每个人，请先详细检查数据库，以查看它是否不是从那里来的，而不是从您的代码来的.
EDIT : Actually it seems like the errors where comming directly from the database, the moderators can delete this post if they want. However I keep Trashgod's response validated as it was more than helpful. For everyone that might come here with a similar issue, inspect in detail your database first to see if it isn't comming from there instead of your code.
推荐答案
追踪数据异常是艰巨的事情，但是JFreeChart至少可以使结果更容易可视化.一些启发式测试:
Chasing down anomalies in data is arduous, but JFreeChart can at least make the result easier to visualize. Some heuristics for testing:
-
要验证表格列表中的假定重复项确实是重复项，请格式化时间戳以包含毫秒，例如将
S添加到SimpleDateFormat或A添加到DateTimeFormatter.
为了进行研究，请将查询直接直接传递到JDBCXYDataset，并添加一个ORDER BY子句(未经测试):
For study, temporarily pass the query directly to JDBCXYDataset, and add an ORDER BY clause (untested):
jds.executeQuery(
"SELECT Date_Heure, PV, SV FROM cmd3 "
+ "WHERE Date_Heure BETWEEN "
+ "2020-06-25 00:00:00 AND 2020-06-26 00:00:00 "
+ "ORDER BY Date_Heure");
像在此处一样，在ChartFactory中启用工具提示，以查看数据值原地.这可能会为您的WHERE子句建议其他条件，例如PV BETWEEN 5.1 AND 5.9.
Enable tooltips in your ChartFactory, as you did here, to see data values in situ. This may suggest additional conditions for your WHERE clause, e.g. PV BETWEEN 5.1 AND 5.9.
使用交互式JFreeChart平移/缩放控件(在此处中进行了讨论)来检查数据；添加合适的按钮，如此处所示，以方便同事查看您的发现.
Use the interactive JFreeChart pan/zoom controls, discussed here to examine the data; add suitable buttons, shown here, if it will make it easier for colleagues to see your findings.
根据设计， JDBCXYDataset 执行由String定义的查询.如果您的设计需要显示PreparedStatement定义的查询中的数据，则可以使用现有的
By design, JDBCXYDataset executes a query defined by a String. If your design needs to display data from a query defined by a PreparedStatement, you can use the existing implementation as a guide.
public class PreparedDataset extends AbstractXYDataset
implements XYDataset, TableXYDataset, RangeInfo {
private final PreparedStatement ps;
public PreparedDataset(PreparedStatement ps) {
this.ps = ps;
}
…
}
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