sql-server - 将逗号分隔值拆分为行

Question

如何从 SQL Server 中的逗号分隔字符串中获取值到行中，以便将它们插入到表中？

例如，使用此数据:

 Declare @string as nvarchar(max);
 Declare @substring as nvarchar(50);
 set @string = "Apple, Banana, Cherry, Orange, Mango"

对于这个例子，我目前硬编码了 set @last = 2，但是 @last 应该包含字符串中的单词数。参数 @substring 将在循环中一个接一个地包含每个水果，我想用它插入到目标表中。

这是我当前的代码，但我对如何将 @last 设置为所需的值感到困惑:

DECLARE @first AS INT
SET @first = 1
DECLARE @step AS INT
SET @step = 1
DECLARE @last AS INT
SET @last = 2

BEGIN TRANSACTION
WHILE(@first <= @last)
BEGIN

INSERT INTO tbFruit(Name)   
VALUES(@substring);

SET @first += @step
END
COMMIT TRANSACTION

Answer 1

您可以一次性完成所有工作，而不是使用 WHILE 循环。所以在这段代码中，它会将值推送到临时表的行中，然后再将其用于 INSERT 到目标表中:

将逗号分隔值拆分为从以下位置获取的行的示例代码:

Convert Comma Separated column value to rows

DECLARE @string AS NVARCHAR(MAX);
DECLARE @substring AS NVARCHAR(50);
SET @string = 'Apple, Banana, Cherry, Orange, Mango'

SELECT Split.a.value('.', 'VARCHAR(100)') AS Fruits
INTO   #fruits
FROM   
   (
     SELECT CAST ('<M>' + REPLACE(@string, ', ', '</M><M>') + '</M>' AS XML) AS String
   ) AS A
     CROSS APPLY String.nodes('/M') AS Split ( a ); 

-- show what's in the temp table
SELECT *
FROM   #fruits

此时，您在临时表中的行中有了值，您可以使用它来填充目标表，如下所示:

INSERT INTO tbFruit ( Name )
SELECT Fruits FROM #fruits

-- show what's in the target table
SELECT * FROM   #target_table

-- tidy up
DROP TABLE #fruits

SQL Fiddle Demo

TSQL代码:

 DECLARE @string AS NVARCHAR(MAX) = 'Apple, Banana, Cherry, Orange, Mango'
 DECLARE @substring AS NVARCHAR(50)

 SELECT Split.a.value('.', 'VARCHAR(100)') AS Fruits
 INTO   #fruits
 FROM   ( SELECT    CAST ('<M>' + REPLACE(@string, ', ', '</M><M>') + '</M>' AS XML) AS String
        ) AS A
        CROSS APPLY String.nodes('/M') AS Split ( a )   

 CREATE TABLE #target_table ( Fruits NVARCHAR(50) )

 INSERT INTO #target_table
        ( fruits )
        SELECT  *
        FROM    #fruits

 SELECT * FROM   #target_table

 DROP TABLE #fruits
 DROP TABLE #target_table

结果:

| FRUITS |
|--------|
|  Apple |
| Banana |
| Cherry |
| Orange |
|  Mango |