一句sql實現(xiàn)mysql遞歸查詢 sql語句中怎么實現(xiàn)遞歸查詢?
sql語句中怎么實現(xiàn)遞歸查詢?在SQL SERVER 2000 中你可以先一些自定義函數(shù),或一些存儲過程,實現(xiàn)遞歸: select level,TypeName from ProductType t
sql語句中怎么實現(xiàn)遞歸查詢?
在SQL SERVER 2000 中你可以先一些自定義函數(shù),或一些存儲過程,實現(xiàn)遞歸: select level,TypeName from ProductType t START WITH t.ParentID=0 CONNECT BY PRIOR t.ProductTypeID= t.ParentID
SQL數(shù)據(jù)庫實現(xiàn)遞歸查詢的幾種代碼方法?
先明確思路再想實現(xiàn)方法:
思路:首先,start_date和end_date之間是連續(xù)的,因此需要將start_date和end_date轉(zhuǎn)換成一列,如:
實現(xiàn)方法:通過oracle的connect by遞歸方法即可實現(xiàn),代碼如下:
mysql中如何實現(xiàn)遞歸,不要采用自己寫的函數(shù),也不要用存儲過程,就單純的sql可以搞定么?
withaas
(select*fromtable1whereparentid=0
unionall
selectb.*froma,table1bwherea.id=b.parentid)
select*froma
用withas來實現(xiàn)遞歸
sql怎么遞歸查詢的方法?
在SQLSERVER2000中你可以先一些自定義函數(shù),或一些存儲過程,實現(xiàn)遞歸:selectlevel,TypeNamefromProductTypetSTARTWITHt.ParentID=0CONNECTBYPRIORt.ProductTypeID=t.ParentID
如何利用SQLServerWithAs遞歸獲取層級關(guān)系數(shù)據(jù)?
WITH DirectReports(ManagerID, EmployeeID, Title, EmployeeLevel) AS ( SELECT ManagerID, EmployeeID, Title, 0 AS EmployeeLevel FROM dbo.MyEmployees WHERE ManagerID IS NULL UNION ALL --主要是在此,增加一個union all SELECT e.ManagerID, e.EmployeeID, e.Title, EmployeeLevel 1 FROM dbo.MyEmployees AS e INNER JOIN DirectReports AS d -- 在此調(diào)用自身,就可以實現(xiàn)遞歸了 ON e.ManagerID = d.EmployeeID ) SELECT ManagerID, EmployeeID, Title, EmployeeLevel FROM DirectReports ORDER BY ManagerID