how to split and insert CSV data into a new table in single statement?

Question

I have a table named "Documents" containing a column as below:

DocumentID

I have data in the format - @DocID = 1,2,3,4

How do I insert these documentID's in separate rows using a single query?

Answer 1

If I understand right you want to do this:

INSERT INTO Documents
(DocumentID)
SELECT 1
UNION
SELECT 2
UNION
SELECT 3
UNION
SELECT 4

Answer 2

You need a way to split and process the string in TSQL, there are many ways to do this. This article covers the PROs and CONs of just about every method:

Arrays and Lists in SQL Server 2005 and Beyond

You need to create a split function. This is how a split function can be used:

SELECT
    *
    FROM YourTable                               y
    INNER JOIN dbo.yourSplitFunction(@Parameter) s ON y.ID=s.Value

I prefer the number table approach to split a string in TSQL - Using a Table of Numbers but there are numerous ways to split strings in SQL Server, see the previous link, which explains the PROs and CONs of each.

For the Numbers Table method to work, you need to do this one time table setup, which will create a table Numbers that contains rows from 1 to 10,000:

SELECT TOP 10000 IDENTITY(int,1,1) AS Number
    INTO Numbers
    FROM sys.objects s1
    CROSS JOIN sys.objects s2
ALTER TABLE Numbers ADD CONSTRAINT PK_Numbers PRIMARY KEY CLUSTERED (Number)

Once the Numbers table is set up, create this split function:

CREATE FUNCTION inline_split_me (@SplitOn char(1),@param varchar(7998)) RETURNS TABLE AS
   RETURN(SELECT substring(@SplitOn + @param + ',', Number + 1,
                    charindex(@SplitOn, @SplitOn + @param + @SplitOn, Number + 1) - Number - 1)
                 AS Value
          FROM   Numbers
          WHERE  Number <= len(@SplitOn + @param + @SplitOn) - 1
            AND  substring(@SplitOn + @param + @SplitOn, Number, 1) = @SplitOn)

GO 

You can now easily split a CSV string into a table and join on it:

select * from dbo.inline_split_me(';','1;22;333;4444;;') where LEN(Value)>0

OUTPUT:

Value
----------------------
1
22
333
4444

(4 row(s) affected)

to make you new table use this:

--set up tables:
DECLARE @Documents table (DocumentID varchar(500), SomeValue varchar(5))
INSERT @Documents VALUES ('1,2,3,4','AAA')
INSERT @Documents VALUES ('5,6'    ,'BBBB')

DECLARE @NewDocuments table (DocumentID int, SomeValue varchar(5))

--populate NewDocuments
INSERT @NewDocuments
    (DocumentID, SomeValue)
SELECT
    c.value,a.SomeValue
    FROM @Documents    a
        CROSS APPLY dbo.inline_split_me(',',a.DocumentID) c

 --show NewDocuments contents:
select * from @NewDocuments

OUTPUT:

DocumentID  SomeValue
----------- ---------
1           AAA
2           AAA
3           AAA
4           AAA
5           BBBB
6           BBBB

(6 row(s) affected)

if you don't want to create a Numbers tableand are running SQL Server 2005 and up, you can just use this split function (no Numbers table required):

CREATE FUNCTION inline_split_me (@SplitOn char(1),@String varchar(7998))
RETURNS TABLE AS
RETURN (WITH SplitSting AS
           (SELECT
                LEFT(@String,CHARINDEX(@SplitOn,@String)-1) AS Part
                    ,RIGHT(@String,LEN(@String)-CHARINDEX(@SplitOn,@String)) AS Remainder
                WHERE @String IS NOT NULL AND CHARINDEX(@SplitOn,@String)>0
            UNION ALL
            SELECT
                LEFT(Remainder,CHARINDEX(@SplitOn,Remainder)-1)
                    ,RIGHT(Remainder,LEN(Remainder)-CHARINDEX(@SplitOn,Remainder))
                FROM SplitSting
                WHERE Remainder IS NOT NULL AND CHARINDEX(@SplitOn,Remainder)>0
            UNION ALL
            SELECT
                Remainder,null
                FROM SplitSting
                WHERE Remainder IS NOT NULL AND CHARINDEX(@SplitOn,Remainder)=0
           )
           SELECT Part FROM SplitSting
       )
GO

Answer 3

+1 for KM's thorough explanation. This will get the job done quickly but maybe not necessarily most efficiently (again see KM's response for all the options)

My quick response:

Install SQL# (it's free and very useful)

Then

INSERT INTO Documents (documentId)
SELECT SplitVal FROM SQL#.String_Split(@DocId, ',', 1)