数据库元数据获取列详细信息

发布于 2024-10-01 09:05:16 字数 690 浏览 3 评论 0原文

我使用数据库元数据来查找列大小。但 getColumns(null,null,"table_name",null) 返回一个空结果集。我通过查询来检查该表，并且该表存在。错误在哪里？提前致谢！

更新：

Connection connection = getConnection(); //getting the connection -   
Statement st = connection.createStatement();  
ResultSet rs = st.executeQuery("select * from table_name");  
while (rs.next()) { 
   System.out.println(rs.getString("column_name")); //The values get printed 
}
ResultSet rsColumns = null;
DatabaseMetaData meta = connection.getMetaData();
rsColumns = meta.getColumns(null, null, "table_name",null);     
System.out.println(rsColumns.next()); // I get false here which means resultset is empty. But I dunno why.

原文

I use databasemetadata to find the column size. But getColumns(null,null,"table_name",null) returns an empty resultset. I checked for the table by querying it and the table is present. Where is the error? Thanks in advance!

Update:

Connection connection = getConnection(); //getting the connection -   
Statement st = connection.createStatement();  
ResultSet rs = st.executeQuery("select * from table_name");  
while (rs.next()) { 
   System.out.println(rs.getString("column_name")); //The values get printed 
}
ResultSet rsColumns = null;
DatabaseMetaData meta = connection.getMetaData();
rsColumns = meta.getColumns(null, null, "table_name",null);     
System.out.println(rsColumns.next()); // I get false here which means resultset is empty. But I dunno why.

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

情话已封尘 2024-10-08 09:05:16

您使用哪个数据库？这可能与它如何处理不带引号的标识符有关，遵循标准的数据库会自动将它们存储为大写。您可以通过调用 storesUpperCaseIdentifiers 方法以编程方式检查它是否执行此操作。

解决方案是在创建表时使用带引号的标识符，或者如果 storesUpperCaseIdentifiers 返回 true，则对表名称字符串调用 toUpperCase 方法。

回复收藏 0 原文

网白 2024-10-08 09:05:16

您可以尝试以下代码片段吗：

ResultSet rsColumns = null;
DatabaseMetaData meta = connection.getMetaData();
rsColumns = meta.getColumns(null, null, "table_name",null);     
While (rsColumns,next()) {
System.out.println(rsColumns.getInt("COLUMN_SIZE"));
}

我认为您缺少“COLUMN_SIZE”。

Can you try the below snippet:

ResultSet rsColumns = null;
DatabaseMetaData meta = connection.getMetaData();
rsColumns = meta.getColumns(null, null, "table_name",null);     
While (rsColumns,next()) {
System.out.println(rsColumns.getInt("COLUMN_SIZE"));
}

I think you are missing the "COLUMN_SIZE".

回复收藏 0 原文

~没有更多了~