Java JDBC ResultSet无法存储查询结果

我目前正试图通过JDBC在Oracle数据库上运行查询。我已经在SQLDeveloper中测试了我的查询，但是当我尝试在Java程序中运行查询时，我的ResultSet rs.next（）结果返回false（意味着rs中没有存储任何内容）

我的代码如下：

public static void testFunction() {
    Properties properties = new Properties();
    properties.put("user", "USERNAMEHERE");
    properties.put("password", "PASSWORDHERE");

    String URL = "jdbc:oracle:thin:@abc:123:def456";
    Connection conn = null;
    PreparedStatement stmt = null;
    ResultSet rs = null;
    String sqltxt = "SELECT a.MESSAGE, a.DATE, a.ID_NUM, b.MESSAGE, b.ANOTHER_ID FROM USER.SOME_TABLE_NAME a INNER JOIN USER.DIFFERENT_TABLE_NAME b on a.MESSAGE = b.MESSAGE where a.DATE= '1-December-2014' and b.ANOTHER_ID = 3 and a.ID_NUM IN(0, 100)";


    try {
        conn = DriverManager.getConnection(URL, properties);
        stmt = conn.prepareStatement(sqltxt, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
        rs = stmt.executeQuery();
        System.out.println("Records exist? " + rs.next());
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try { if (rs != null) rs.close(); } catch (Exception e) {};
        try { if (stmt != null) stmt.close(); } catch (Exception e) {};
        try { if (conn != null) conn.close(); } catch (Exception e) {};
    }
}

我注意到，每当我向sqltxt添加WHERE子句时，rs.next（）就会产生false

如果我碰巧自己找到了解决方案，我将把它张贴在这里

编辑：下面是上面相同的代码，但对sqltxt的查询不同：

public static void testFunction() {
    Properties properties = new Properties();
    properties.put("user", "USERNAMEHERE");
    properties.put("password", "PASSWORDHERE");

    String URL = "jdbc:oracle:thin:@abc:123:def456";
    Connection conn = null;
    PreparedStatement stmt = null;
    ResultSet rs = null;
    String sqltxt = "SELECT MESSAGE FROM USER.SOME_TABLE WHERE DATE = '01-December-2015'";

    try {
        conn = DriverManager.getConnection(URL, properties);
        stmt = conn.prepareStatement(sqltxt, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
        rs = stmt.executeQuery();
        System.out.println("Records exist? " + rs.next());
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try { if (rs != null) rs.close(); } catch (Exception e) {};
        try { if (stmt != null) stmt.close(); } catch (Exception e) {};
        try { if (conn != null) conn.close(); } catch (Exception e) {};
    }
}

---

您应该避免在SQL文本中使用硬编码日期。尤其是对于Oracle，它需要大量的工作。以下是两个答案，一个使用硬编码日期，另一个正确利用

PreparedStatement

对象的功能：

在线日期：

public static void testFunction() {
    Properties properties = new Properties();
    properties.put("user", "USERNAMEHERE");
    properties.put("password", "PASSWORDHERE");

    String URL = "jdbc:oracle:thin:@abc:123:def456";
    Connection conn = null;
    PreparedStatement stmt = null;
    ResultSet rs = null;
    String sqltxt = "SELECT MESSAGE FROM USER.SOME_TABLE WHERE DATE = to_date('01-December-2015', 'dd-month-yyyy')";

    try (Connection conn = DriverManager.getConnection(URL, properties);
        PreparedStatement stmt = conn.prepareStatement(sqltxt, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
        ResultSet rs = stmt.executeQuery();) {

        System.out.println("Records exist? " + rs.next());
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static void testFunction() {
    Properties properties = new Properties();
    properties.put("user", "USERNAMEHERE");
    properties.put("password", "PASSWORDHERE");

    String URL = "jdbc:oracle:thin:@abc:123:def456";
    String sqltxt = "SELECT MESSAGE FROM USER.SOME_TABLE WHERE DATE = ?";

    try (Connection conn = DriverManager.getConnection(URL, properties);
        PreparedStatement stmt = conn.prepareStatement(sqltxt, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
        ResultSet rs = stmt.executeQuery();) {

        stmt.setDate(1, Date.valueOf(LocalDate.now().withYear(2015).withMonth(12).withDayOfMonth(1)));
        System.out.println("Records exist? " + rs.next());
    } catch (Exception e) {
        e.printStackTrace();
    }
}

（有关Oracle中硬编码日期的更多信息，请参阅）

通过参数化SQL的日期：

public static void testFunction() {
    Properties properties = new Properties();
    properties.put("user", "USERNAMEHERE");
    properties.put("password", "PASSWORDHERE");

    String URL = "jdbc:oracle:thin:@abc:123:def456";
    Connection conn = null;
    PreparedStatement stmt = null;
    ResultSet rs = null;
    String sqltxt = "SELECT MESSAGE FROM USER.SOME_TABLE WHERE DATE = to_date('01-December-2015', 'dd-month-yyyy')";

    try (Connection conn = DriverManager.getConnection(URL, properties);
        PreparedStatement stmt = conn.prepareStatement(sqltxt, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
        ResultSet rs = stmt.executeQuery();) {

        System.out.println("Records exist? " + rs.next());
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static void testFunction() {
    Properties properties = new Properties();
    properties.put("user", "USERNAMEHERE");
    properties.put("password", "PASSWORDHERE");

    String URL = "jdbc:oracle:thin:@abc:123:def456";
    String sqltxt = "SELECT MESSAGE FROM USER.SOME_TABLE WHERE DATE = ?";

    try (Connection conn = DriverManager.getConnection(URL, properties);
        PreparedStatement stmt = conn.prepareStatement(sqltxt, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
        ResultSet rs = stmt.executeQuery();) {

        stmt.setDate(1, Date.valueOf(LocalDate.now().withYear(2015).withMonth(12).withDayOfMonth(1)));
        System.out.println("Records exist? " + rs.next());
    } catch (Exception e) {
        e.printStackTrace();
    }
}

---

阅读：有关在Java中使用参数化SQL的更多信息。

我将尝试注释/删除部分查询以缩小问题范围。（

a.DATE='2014年12月1日'

如果你身边有DBA，那就值得怀疑了）我添加了一个代码的替代版本，使用了一个更简单的SQL语句，它仍然会给我假消息，但我希望它有助于缩小问题：）我想问题就在这里：

。。。日期='2014年12月1日'..

。将其更改为

DATE=to_DATE（'2014-12-01'，'yyyy-mm-dd'）

。永远不要依赖隐式转换，它们可以在某些环境（语言设置）中工作，但在其他环境中可能会失败。请尝试使用“2015-12-01”作为日期值（另请参见：）@Abhishek查看下面的答案。非常感谢，我非常喜欢参数化SQLmethod@Abhishek一定要对每一个有价值的答案进行投票。@BasilBourque我投了赞成票，但是我还没有足够的声誉在整个网站上反映出来