Sql Server2005 query problem

问题

i have a table which contains the following fields

• Supervisorid
• Empid

This is just like a referral program. A guy can refer 3 guys under him i.e, 3 is referring three guys namely 4 5 8 similarly 4 is referring 9 10 and 11 likewise 8 is referring 12, 13 it goes like this..

I want a query to get the total no of down line members under a guy say 3

回答1:

You can make use of Recursive CTE.

Something like this

DECLARE @Table TABLE(
        Supervisorid INT,
        Empid INT
)

INSERT INTO @Table SELECT 3, 4
INSERT INTO @Table SELECT 3, 5
INSERT INTO @Table SELECT 3, 8

INSERT INTO @Table SELECT 4, 9
INSERT INTO @Table SELECT 4, 10
INSERT INTO @Table SELECT 4, 11

INSERT INTO @Table SELECT 8, 12
INSERT INTO @Table SELECT 8, 13

DECLARE @ID INT
SELECT  @ID = 3

;WITH Vals AS (
        SELECT  *
        FROM    @Table
        WHERE   SuperVisorID = @ID
        UNION ALL
        SELECT  v.SuperVisorID,
                t.Empid
        FROM    Vals v INNER JOIN
                @Table t    ON  v.Empid = t.Supervisorid
)
SELECT  SuperVisorID,
        COUNT(Empid) Total
FROM    Vals
GROUP BY    SuperVisorID

来源：https://stackoverflow.com/questions/3993927/sql-server2005-query-problem