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SqlCommand com = new SqlCommand("select * from myuser where username=@UserName and password=@Pwd", con);
com.Parameters.Add(new SqlParameter("@UserName", UserName));
com.Parameters.Add( new SqlParameter("@Pwd",Pwd));
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create PROCEDURE pagelist
@tablename nvarchar(50),
@fieldname nvarchar(50)='*',
@pagesize int output,--ÿҳÏÔʾ¼Ç¼ÌõÊý
@currentpage int output,--µÚ¼¸Ò³
@orderid nvarchar(50),--Ö÷¼üÅÅÐò
@sort int,--ÅÅÐò·½Ê½£¬1±íʾÉýÐò£¬0±íʾ½µÐòÅÅÁÐ
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select getdate()
2. dateadd ÔÚÏòÖ¸¶¨ÈÕÆÚ¼ÓÉÏÒ»¶Îʱ¼äµÄ»ù´¡ÉÏ£¬·µ»ØÐ嵀 datetime Öµ
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select dateadd(day,2,'2004-10-15') --·µ»Ø£º2004-10-17 00:00:00.000
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SELECT c.CustomerId, CompanyName
from Customers c
WHERE EXISTS(
SELECT OrderID from Orders o
WHERE o.CustomerID = cu.CustomerID)
ÕâÀïÃæµÄEXISTSÊÇÈçºÎÔË×÷ÄØ£¿×Ó²éѯ·µ»ØµÄÊÇOrderId×ֶΣ¬¿ÉÊÇÍâÃæµÄ²éѯҪÕÒµÄÊÇCustomerIDºÍCompanyName×ֶΣ¬ÕâÁ½¸ö×Ö¶Î¿Ï ......
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ORACLE ²ÉÓÃÁ½ÖÖ·ÃÎʱíÖмǼµÄ·½Ê½:
a. È«±íɨÃè
È«±íɨÃè¾ÍÊÇ˳ÐòµØ·ÃÎʱíÖÐÿÌõ¼Ç¼. ORACLE²ÉÓÃÒ»´Î¶ÁÈë¶à¸öÊý¾Ý¿é(database block)µÄ·½Ê½ÓÅ»¯È«±íɨÃè.
b. ͨ¹ýROWID·ÃÎʱí
Äã¿ÉÒÔ²ÉÓûùÓÚROWIDµÄ·ÃÎÊ·½Ê½Çé¿ö,Ìá¸ß·ÃÎʱíµÄЧÂÊ, , ROWID°üº¬Á˱íÖмǼµ ......
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select distinct(employeeid) from orders
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select orders.EmployeeID,Employees.EmployeeID
from orders INNER JOIN Employees
on Employees.EmployeeID=orders.EmployeeID
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