从不可解析的表SQL Server查询和导出

Question

First I am sorry for my bad English, is not my language.

My problem is: I have a table with around 10 million records of transaction of bank. It don't have PK and didn't sort as any column.

My work is create a page to filter and export it to csv. But limit of rows to export Csv is around 200k records.

I have some idea like:

• create 800 tables of 800 ATMs (just an idea, I know it's stupid) and send data from main table to it 1 time per day => export to 800 file csv

• use Linq to get 100k record per time then next time, I skip those. But I am stuck when Skip command need OrderBy and I got OutOfMemoryException with it

   db.tblEJTransactions.OrderBy(u => u.Id).Take(100000).ToList() 

Can anyone help me, every idea is welcome (my boss said I can use anything includes create hundred of tables, use Nosql ... )

Answer 1

If you don't have a primary key in your table, then add one. The simplest and easiest is to add an int IDENTITY column.

ALTER TABLE dbo.T 
ADD ID int NOT NULL IDENTITY (1, 1)

ALTER TABLE dbo.T 
ADD CONSTRAINT PK_T PRIMARY KEY CLUSTERED (ID)

If you can't alter the original table, create a copy.

Once the table has a primary key you can sort by it and select chunks/pages of 200K rows with predictable results.

Answer 2

I'm not sure about my solution. But you can refer and try it:

select top 1000000 *, row_number() over (order by (select null)) from tblEJTransactions

The above query returns sorted list.

And then you can use Linq to get the result.