尝试在表中插入行时出现SQL语法错误异常

Question

嗨，我无法执行以下功能而没有遇到以下异常。我不确定为什么会这样。我认为这可能与报价有关。如果有问题，我正在使用derby数据库。

java.sql.SQLSyntaxErrorException

这是我尝试执行的以下代码：

public void addAlbum(Album album) throws IOException, SQLException {
    Properties props = new Properties();
    FileInputStream in = new FileInputStream("database.properties");
    props.load(in);
    in.close();

    props.getProperty("jdbc.drivers");
    String url = props.getProperty("jdbc.url");
    String username = props.getProperty("jdbc.username");
    String password = props.getProperty("jdbc.password");

    Connection connection = DriverManager.getConnection(url, username, password);
    Statement statement = connection.createStatement();
    String sql = null;

    if(album instanceof CDAlbum) {
        CDAlbum cdAlbum = (CDAlbum)album;
        sql = "INSERT INTO MyAlbums VALUES ('CD', '" + cdAlbum.getTitle() + "', '" + cdAlbum.getGenre() + "','" + cdAlbum.getArtist() + "', '" + cdAlbum.getTracks() + "');";
    }
    if(album instanceof DVDAlbum) {
        DVDAlbum dvdAlbum = (DVDAlbum)album;
        sql = "INSERT INTO MyAlbums VALUES ('DVD', '" + dvdAlbum.getTitle() + "', '" + dvdAlbum.getGenre() + "','" + dvdAlbum.getDirector() + "', '" + dvdAlbum.getPlotOutline() + "');";
    }

    statement.executeUpdate(sql);
    System.out.println("Album Added!");

    if(statement != null) {
        statement.close();
    }
    if(connection != null) {
        connection.close();
    }
}

这是例外：

java.sql.SQLSyntaxErrorException: Syntax error: Encountered "t" at line 2, column 5.
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.EmbedStatement.execute(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedStatement.executeLargeUpdate(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedStatement.executeUpdate(Unknown Source)
at au.edu.uow.CollectionDB.MyCollectionDB.addAlbum(MyCollectionDB.java:194)
at au.edu.uow.Collection.CollectionFactory.loadCollection(CollectionFactory.java:136)
at MyCollection.main(MyCollection.java:18)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)
Caused by: ERROR 42X01: Syntax error: Encountered "t" at line 2, column 5.
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.ParserImpl.parseStatementOrSearchCondition(Unknown Source)
at org.apache.derby.impl.sql.compile.ParserImpl.parseStatement(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)
... 11 more

Answer 1

您的代码中有两个问题：

1. SQL语句;最后不需要分号。它将使代码失败。

2. 该代码易于进行SQL注入并且难以维护。请PreparedStatement改用：

这应该是工作代码：

String sql = "INSERT INTO MyAlbums VALUES (?, ?, ?, ?, ?)";
PreparedStatement pstmt = connection.prepareStatement(sql);
if(album instanceof CDAlbum) {
    pstmt.setString(1, "CD");
    CDAlbum cdAlbum = (CDAlbum)album;
    pstmt.setString(4, cdAlbum.getArtist());
    pstmt.setString(5, cdAlbum.getTracks());
}
if(album instanceof DVDAlbum) {
    pstmt.setString(1, "DVD");
    DVDAlbum dvdAlbum = (DVDAlbum)album;
    pstmt.setString(4, dvdAlbum.getDirector());
    pstmt.setString(5, dvdAlbum.getPlotOutline());
}
pstmt.setString(2, album.getTitle());
pstmt.setString(3, album.getGenre());
pstmt.executeUpdate();

在 大 平原字符串连接而这种做法对于你的情况之间的区别就是PreparedStatement参数会逃跑任何'和"和其他字符你。