1.使用 SQL 中的递归查询(Recursive CTE)来实现。以下是使用 T-SQL 语法的示例代码: WITHNumbersAS(SELECT1ASNumberUNIONALLSELECTNumber+1FROMNumbersWHERENumber<50)SELECTNumberFROMNumbersOPTION(MAXRECURSION0) 在这个示例中,我们创建了一个名为Numbers的递归公用表表达式(Recursive CTE),它包含一个初始记录(数字1)...
WHILE is very simple to understand, but it is not so efficient. Database developers usually try to solve the previous problem using CTEs. CTE stands for Common Table Expressions which is a temporary named result set. CTEs are very powerful because they can refer to themselves (recursive common...
WITH RECURSIVE语句是 SQL 中的一种特殊的公用表表达式(CTE),用于执行递归查询。递归查询对于处理层级结构的数据非常有用,例如组织结构图、文件目录树等。递归CTE由两个部分组成:递归的基础部分和递归部分。下面详细讲解WITH RECURSIVE的语法和用法。 基本语法 WITH RECURSIVE的基本语法如下: sql复制代码 WITH RECURSIVE ...
How to get OLD value while writting AFTER UPDATE trigger How to get records that have same id but different name? How to get rid of Warning: Null value is eliminated by an aggregate or other SET operation. How to get row_number in sequence in recursive CTE How to get save result from...
there is a way of doing all this without using recursive triggers, such as a recursive CTE. ...
Nested loop collections can be classified into indexed nesting and temporary Index Nested Loop Join. 42. Explain Common Table Expression SQL. In general, a Common Table Expression (CTE) is a temporary, named result set that can be used to refer to an UPDATE, INSERT, SELECT, or DELETE ...
可以使用MAXRECURSION来防止不合理的递归 CTE 进入无限循环。 下面的示例特意创建了一个无限循环,然后使用MAXRECURSION提示将递归级别限制为两级。 SQL --Creates an infinite loopWITHcte (EmployeeID, ManagerID, Title)AS(SELECTEmployeeID, ManagerID, TitleFROMdbo.MyEmployeesWHEREManagerIDISNOTNULLUNIONALLSELECTcte...
When making a recursive CTE you divide it into two sections joined by aUNION ALLwhere the first section is the anchor, and is only called once, while the second section do the recursion and is called repeatedly until it returns an empty result. ...
How to get OLD value while writting AFTER UPDATE trigger How to get records that have same id but different name? How to get rid of Warning: Null value is eliminated by an aggregate or other SET operation. How to get row_number in sequence in recursive CTE How to get save result from...
SQL CTE – Common Table Expression SQL Recursive WITH CTE (Common Table Expression) queries ORDER BY How to sort a SQL query result set randomly Window Functions Why you should definitely learn SQL Window Functions How to calculate percentiles with SQL PERCENTILE_CONT ...