Repeat Rows N Times According to Column Value

问题:

I have following table.

Table A:
ID         ProductFK         Quantity       Price
------------------------------------------------
10         1                  2           100
11         2                  3           150
12         1                  1           120
----------------------------------------------

I need select that repeat Rows N Time According to Order Column Value.

So I need following select result:

ID        ProductFK         Quantity        Price
------------------------------------------------
10        1                   1          100
10        1                   1          100
11        2                   1          150
11        2                   1          150
11        2                   1          150
12        1                   1          120

回答1:

You could do that with a recursive CTE using UNION ALL:

;WITH cte AS
  (
    SELECT * FROM Table1

    UNION ALL

    SELECT cte.[ID], cte.ProductFK, (cte.[Order] - 1) [Order], cte.Price
    FROM cte INNER JOIN Table1 t
      ON cte.[ID] = t.[ID]
    WHERE cte.[Order] > 1
)
SELECT [ID], ProductFK, 1 [Order], Price
FROM cte
ORDER BY 1

Here's a working SQLFiddle.

Here's a longer explanation of this technique.

---

Since your input is too large for this recursion, you could use an auxillary table to have "many" dummy rows and then use SELECT TOP([Order]) for each input row (CROSS APPLY):

;WITH E00(N) AS (SELECT 1 UNION ALL SELECT 1),
      E02(N) AS (SELECT 1 FROM E00 a, E00 b),
      E04(N) AS (SELECT 1 FROM E02 a, E02 b),
      E08(N) AS (SELECT 1 FROM E04 a, E04 b),
      E16(N) AS (SELECT 1 FROM E08 a, E08 b)
SELECT t.[ID], t.ProductFK, 1 [Order], t.Price
FROM Table1 t CROSS APPLY (
  SELECT TOP(t.[Order]) N
  FROM E16) ca
ORDER BY 1

(The auxillary table is borrowed from here, it allows up to 65536 rows per input row and can be extended if required)

Here's a working SQLFiddle.

回答2:

You can use a simple JOIN to get the desired result as below:

SELECT  t1.*, t2.number + 1 RepeatNumber
FROM    TableA t1
JOIN    master.dbo.spt_values t2 ON t2.type = 'P' AND t2.number < t1.Quantity

The above query repeats each record by the specified number in Quantity column.

Note for master.dbo.spt_values on type = 'P':
This table is used for getting a series of number which is hard-coded in it by
condition of type = 'P'.

回答3:

You can simply join the table to itself

SELECT T1.*
FROM T T1 JOIN T T2
ON T1.[Quantity] >= T2.[Quantity]
ORDER BY T1.[ID];

Returns:

+----+-----------+----------+----------+
| ID | ProductFK | Quantity |  Price   |
+----+-----------+----------+----------+
| 10 |         1 |        2 | 100.0000 |
| 10 |         1 |        2 | 100.0000 |
| 11 |         2 |        3 | 150.0000 |
| 11 |         2 |        3 | 150.0000 |
| 11 |         2 |        3 | 150.0000 |
| 12 |         1 |        1 | 120.0000 |
+----+-----------+----------+----------+

Demo

回答4:

CREATE TAblE #temp
(
T_Name      VARCHAR(50),
T_Times      BIGINT
)

INSERT INTO #temp(T_Name,T_Times) VALUES ('ASHISH',4)
INSERT INTO #temp(T_Name,T_Times) VALUES ('PANKAJ',3)
INSERT INTO #temp(T_Name,T_Times) VALUES ('RUPESH',2)
INSERT INTO #temp(T_Name,T_Times) VALUES ('MANISH',5)

SELECT t.T_Name ,t.T_Times FROM
(SELECT  T_Name,T_Times,CAST(('<val>'+REPLICATE(T_Name+'</val><val>',T_Times-1)
+'</val>') AS XML )AS X FROM #temp)t CROSS APPLY t.X.nodes('/val')y(z)

drop table #temp