It turns out that there is no serious consideration. SQL Server
Record1Record2 ... Recordn ... Recordn m ......
Result1: Select Top N M from Tablename Order By Field1; / * Field1's order is the order of the table * /
Record1Record2 ... Recordn ... Recordn M
Result2: SELECT TOP M from Result1 ORDER by Field1 DESC;
Recordn MRecordn M-1 ... Recordn
Result3: Select * from result2 order by field2;
The last statement is: SELECT * FROM (SELECT TOP N M from Tablename Order by Field1) Order By Field1 DESC) Order by Field1;
2004-7-30 Completion (suitable in Oracle below):
There is a problem with this, if m is a statement that has been ORDER BY, the outer ORDER BY may also destroy the inner layer of Order By, so it is necessary to add a layer of constraint, and Field1 must be the first field of the inner order by. After a simple test, this is ok, the test case is behind.
Another method of acquiring N to N M strip is:
SQL> Select * from (select rownum as xfdgdf, tablename. * From tablename oritable) Where xfdgdf betWeen n and N m;
The above is more than a field XfDGDF, but how is it? ?
SQL> Select Custid, CustName from Customer;
Custid custom ---------- -------------------- 35 444 35 6666 445 676 35 AAA 35 5555
SQL> Select Custid, CustName from Customer Order by Custid, Custname
Custid customAme ---------- -------------------- 35 444 35 5555 35 6666 35 AAA 445 676
SQL> SELECT * FROM (SELECT * "Order by Custid DESC) Order by Custid Desc;
Custid customAme ---------- -------------------- 35 444 35 5555 35 6666 35 AAA 445 676
July 31:
Note: SELECT * from Tablename Where Rownum> 10 can't take out the record of Rownum behind Rownum
Today, another method is found, but there is no test. I don't know if the efficiency is not higher than the above method efficiency. There is no problem to solve the problem of more fields. From
http://blog.codelphi.com/progame/archive/2004/02/21/1456.aspxselect rownum, * from MyTable Where Rownum <10 minusselect Rownum, * from MyTable Where Rownum <5
This method should be relatively universal than the above method, and may be implemented in a similar method in SQL Server.
SELECT TOP 10 * from MyTable Minusselect Top 5 * from MyTable
