java - Derby INSERT SELECT 空指针异常

Question

我正在编写一个通过 JDBC 与 Apache Derby 配合使用的 Java 应用程序。我在使用以下代码片段中的代码时遇到问题:

byte md5[] = md5sum(file);

PreparedStatement s = con.prepareStatement("INSERT INTO input_files (job_ID, hash) SELECT job_id, ? FROM job WHERE job_name = ?");
s.setBytes(1, md5);
s.setString(2, jobName);
s.executeUpdate();
s.close();

这将插入到下表中:

CREATE TABLE input_files
(
    hash char(16) for bit data,
    job_id integer REFERENCES job,
    PRIMARY KEY(job_id, hash)
);

CREATE TABLE job
(
    job_id integer PRIMARY KEY GENERATED ALWAYS as IDENTITY,
    job_name character varying(50) UNIQUE NOT NULL,
    #other fields
);

这个想法是有一个内部整数 job_id它由数据库内部使用，但我们希望尽可能使用人类可读的字符串 job_name 来引用它

这始终会抛出以下异常。

java.sql.SQLException: Java exception: ': java.lang.NullPointerException'.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.javaException(Unknown Source)
    at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(UnknownSource)
    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.EmbedPreparedStatement20.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement30.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement40.<init>(Unknown Source)
    at org.apache.derby.jdbc.Driver40.newEmbedPreparedStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at [line 3 of snippet above]

正如您所看到的，这是从创建准备好的语句的行抛出的 - 它并没有达到执行它的程度。我究竟做错了什么？完全相同的准备好的语句在 PostgreSQL 中工作得很好。

[编辑] Derby 日志:

----------------------------------------------------------------
2010-08-18 08:47:08.779 GMT:
 Booting Derby version The Apache Software Foundation - Apache Derby - 10.6.1.0 - (938214): instance a816c00e-012a-8461-611c-0000046700d0 
on database directory /path/to/myDatabase   with class loader sun.misc.Launcher$AppClassLoader@6d6f0472

Database Class Loader started - derby.database.classpath=''
2010-08-18 08:47:12.067 GMT Thread[SwingWorker-pool-1-thread-1,5,main] (XID = 316), (SESSIONID = 1), (DATABASE = myDatabase), (DRDAID = null), Cleanup action starting
2010-08-18 08:47:12.067 GMT Thread[SwingWorker-pool-1-thread-1,5,main] (XID = 316), (SESSIONID = 1), (DATABASE = myDatabase), (DRDAID = null), Failed Statement is: INSERT INTO input_files (job_id, hash) SELECT job_id, ? FROM job WHERE job_name = ?
java.lang.NullPointerException
    at org.apache.derby.impl.sql.compile.BitTypeCompiler.storable(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumn.checkStorableExpression(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumn.checkStorableExpression(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumnList.checkStorableExpressions(Unknown Source)
    at org.apache.derby.impl.sql.compile.InsertNode.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)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement20.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement30.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement40.<init>(Unknown Source)
    at org.apache.derby.jdbc.Driver40.newEmbedPreparedStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at [line 3 of snippet]
Cleanup action completed

2010-08-18 08:47:12.084 GMT:
Shutting down instance a816c00e-012a-8461-611c-0000046700d0 with class loader sun.misc.Launcher$AppClassLoader@6d6f0472 
----------------------------------------------------------------

和展开的异常:

java.sql.SQLException: Java exception: ': java.lang.NullPointerException'.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.javaException(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.EmbedPreparedStatement20.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement30.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement40.<init>(Unknown Source)
    at org.apache.derby.jdbc.Driver40.newEmbedPreparedStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at [line 3 of snippet above]
Caused by: java.sql.SQLException: Java exception: ': java.lang.NullPointerException'.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)
... 26 more
Caused by: java.lang.NullPointerException
    at org.apache.derby.impl.sql.compile.BitTypeCompiler.storable(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumn.checkStorableExpression(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumn.checkStorableExpression(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumnList.checkStorableExpressions(Unknown Source)
    at org.apache.derby.impl.sql.compile.InsertNode.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)
... 19 more
SQLState: XJ001
Error code: 0
Message: Java exception: ': java.lang.NullPointerException'.
Cause: java.sql.SQLException: Java exception: ': java.lang.NullPointerException'.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.javaException(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.EmbedPreparedStatement20.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement30.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement40.<init>(Unknown Source)
    at org.apache.derby.jdbc.Driver40.newEmbedPreparedStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at [line 3 of snippet above]
Caused by: java.lang.NullPointerException
    at org.apache.derby.impl.sql.compile.BitTypeCompiler.storable(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumn.checkStorableExpression(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumn.checkStorableExpression(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumnList.checkStorableExpressions(Unknown Source)
    at org.apache.derby.impl.sql.compile.InsertNode.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)
... 19 more
Cause:  java.lang.NullPointerException
    at org.apache.derby.impl.sql.compile.BitTypeCompiler.storable(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumn.checkStorableExpression(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumn.checkStorableExpression(Unknown Source)
    at org.apache.derby.impl.sql.compile.ResultColumnList.checkStorableExpressions(Unknown Source)
    at org.apache.derby.impl.sql.compile.InsertNode.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)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement20.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement30.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedPreparedStatement40.<init>(Unknown Source)
    at org.apache.derby.jdbc.Driver40.newEmbedPreparedStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at [line 3 of snippet above]

Answer 1

此上下文中的空指针异常 - 特别是当相同的 JDBC 代码与另一个 DBMS 配合使用时 - 看起来您遇到了 Derby JDBC 驱动程序中的错误。即使您犯了一个错误并传递了错误的数据或空指针，驱动程序也应该检测到并报告错误，而不是崩溃。