逐页显示网格视图中的数据 [英] Displaying data in grid view page by page

问题描述

我在表中有三万多行。加载gridview中的所有数据需要很多时间。所以我想一次显示100行。当我点击下一页按钮时，应该显示另外100行。当我单击上一页按钮时，应显示前100行。如果我在文本框中输入第5页，那么我想跳转到第5行。

我还想显示有多少页面。我们可以在vb.net [winform] gridview中实现这个概念。我正在使用数据库PostgreSQL。

任何人可以给我一个提示或一些概念？

解决方案

请查看PostgreSQL中的 OFFSET和LIMIT 。< br>
您对第5页的查询可能如下所示：

  SELECT * 
 FROM tbl 
 ORDER BY id 
 OFFSET 400 
 LIMIT 100; 
  

id 是主键在我的例子中，因此索引自动到位。
如果以这种方式访问​​表格很多，性能可能会从使用

总页数：

  SELECT ceil（1235 :: real / 100）:: int 
 FROM tbl; 
  

如果您想要将数字四舍五入，只需简化为：

  SELECT 1235/100 
 FROM tbl; 
  

两个数字都是整数，结果将是一个整数类型，小数位数自动截断。但我想你需要在这里进行整理。

I have more than 30,000 rows in a table. It takes a lot of time to load all the data in the gridview. So I want to display 100 rows at a time. When I click next page button, another 100 rows should be displayed. When I click previous page button, previous 100 rows should be displayed. If I type page 5 in a text box, then I want to jump over to the 5th lot of rows.

I also want to display how many pages there will be. Can we implement this concept in vb.net [winform] gridview. I am using database PostgreSQL.

Can anybody give me a hint or some concept?

解决方案

Look at OFFSET and LIMIT in PostgreSQL.
Your query for the 5th page could look like this:

SELECT * 
FROM   tbl
ORDER  BY id
OFFSET 400
LIMIT  100;

id is the primary key in my example, therefore an index is in place automatically. If you access the table a lot in this fashion, performance may profit from using CLUSTER.

Total number of pages:

SELECT ceil(1235::real / 100)::int
FROM   tbl;

If you wanted the number rounded down, just simplify to:

SELECT 1235  / 100
FROM   tbl;

With both numbers being integer the result will be an integer type and fractional digits truncated automatically. But I think you need to round up here.

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