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java - 无法在Derby数据库中找到表

转载 作者:行者123 更新时间:2023-12-02 09:46:11 27 4
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我无法弄清楚为什么以下程序无法在我的derby数据库中找到表:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;

public class NdConnect
{
public final static String SETUP_FILE_PATH = "/AppData/Local/NewdawnTest";
private static final String CONNECTION_URL = "jdbc:derby:" + "C:/Users/" + System.getenv("USERNAME") + SETUP_FILE_PATH + "db" + ";create=true";
private static Connection conn = null;
private final static Properties dbProperties = new Properties();
private static PreparedStatement pstmtSelectTxns;

public static void connect() {
try {
conn = DriverManager.getConnection(CONNECTION_URL + ";create=true", dbProperties);
pstmtSelectTxns = conn.prepareStatement("SELECT * from TXNS");
System.out.println("Connected OK to " + CONNECTION_URL);
}
catch (SQLException sqle) {
System.out.println("SQL exception");
System.out.println("Connected NOK:The connection URL is " + CONNECTION_URL);
Logger.getLogger(NdConnect.class.getName()).log(Level.SEVERE, null, sqle);
}
}

public static void disconnect()
{
try {
if (conn != null) {
conn.close();
conn = null;
System.out.println("0048 NDC OK:DB closed ");
}
} catch (SQLException sqle) {
Logger.getLogger(NdConnect.class.getName()).log(Level.SEVERE, null, sqle);
}
}

public static void main(String[] args)
{
// NdConnect nd = new NdConnect();
NdConnect.connect();
NdConnect.disconnect();
// System.out.println("NdConnect finished");
}
}

该程序将引发SQLSyntaxErrorException:
run:
SQL exception
Connected NOK:The connection URL is jdbc:derby:C:/Users/Administrator/AppData/Local/NewdawnTestdb;create=true
Nov 25, 2018 6:58:42 AM NdConnect connect
0048 NDC OK:DB closed
SEVERE: null
java.sql.SQLSyntaxErrorException: Table/View 'TXNS' does not exist.
at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown Source)
at org.apache.derby.impl.jdbc.ConnectionChild.handleException(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedPreparedStatement.<init>(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedPreparedStatement42.<init>(Unknown Source)
at org.apache.derby.jdbc.Driver42.newEmbedPreparedStatement(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
at NdConnect.connect(NdConnect.java:21)
at NdConnect.main(NdConnect.java:47)
Caused by: ERROR 42X05: Table/View 'TXNS' does not exist.
at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
at org.apache.derby.impl.sql.compile.FromBaseTable.bindTableDescriptor(Unknown Source)
at org.apache.derby.impl.sql.compile.FromBaseTable.bindNonVTITables(Unknown Source)
at org.apache.derby.impl.sql.compile.FromList.bindTables(Unknown Source)
at org.apache.derby.impl.sql.compile.SelectNode.bindNonVTITables(Unknown Source)
at org.apache.derby.impl.sql.compile.DMLStatementNode.bindTables(Unknown Source)
at org.apache.derby.impl.sql.compile.DMLStatementNode.bind(Unknown Source)
at org.apache.derby.impl.sql.compile.CursorNode.bindStatement(Unknown Source)
at org.apache.derby.impl.sql.GenericStatement.prepMinion(Unknown Source)
at org.apache.derby.impl.sql.GenericStatement.prepare(Unknown Source)
at org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.prepareInternalStatement(Unknown Source)
... 7 more

但是,数据库和表确实存在。我已经通过在Netbeans>服务中创建与数据库的连接来验证了这一点。当我在服务中运行此命令时:
SELECT * from TXNS

所需的表已正确显示,并且输出窗口返回:
Executed successfully in 0 s.
Fetching resultset took 0.016 s.
Line 1, column 1

Execution finished after 0.254 s, no errors occurred.

通过Netbeans服务查看此连接的属性将显示以下属性值:
Display name    NewDawn – TEST DB
Database URL jdbc:derby:C:\Users\Administrator\AppData\Local\NewdawnTest\db
Driver apache_derby_embedded
Driver class org.apache.derby.jdbc.EmbeddedDriver

这似乎与我在Java代码示例中的设置相对应,所以我不明白为什么代码不起作用。

最佳答案

网址不一样:

在Netbeans中:jdbc:derby:C:\Users\Administrator\AppData\Local\NewdawnTest\db
在Java中:jdbc:derby:C:/Users/Administrator/AppData/Local/NewdawnTestdb;create=true
CONNECTION_URL行更改为:

private static final String CONNECTION_URL = "jdbc:derby:" + "C:/Users/" + System.getenv("USERNAME") + SETUP_FILE_PATH + "/db"

关于java - 无法在Derby数据库中找到表,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53465530/

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