SQL 在特定匹配的列中插入值

Question

I have a table consisting of roughly 4000 rows. I am parsing through the column Text in the table and finding every instance of the word 'Fern' and from that the value in the third position of the string I am placing into another column named PONumber . My third column RowKey is an identity column and tells me what rows the word I am searching for is on.

For example the first instance of the word Fern is on row 1 while the next instance is on row 24. I am trying to get the value from the first instance into the PONumber column from row 1-23. The next instance is on row 24 and ends on row 28, so I would need that value in the PONumber column on rows 24-28 and so on....

I am having trouble selecting only that range and placing the value into the corresponding rows in the PONumber column

My code so far:

DECLARE @i INT, @maxCount INT;

select @maxCount = max(RowKey) from Flowers

WHILE @i <= @maxCount
SET @i = 1;
BEGIN
    SELECT Text, PONumber, RowKey FROM Flowers
    WHERE CHARINDEX('Fern', Text) > 0
    
    'I need to grab that value and INSERT INTO Number column

END

Sample Data:

  Text                                      PONumber
1 Fern Flower 12345678  More text           12345678
.                                           12345678
.                                           12345678
.                                           12345678
.                                           12345678
.                                           12345678
.
23
24 Fern Flower 23456789 More text           PONumber
.                                           23456789
.                                           23456789
.                                           23456789
.                                           23456789
29  

    

Answer 1

Considering that all the values are prefixed with 'text' then is seems you could just use CHARINDEX and STUFF to remove that section of text:

SELECT STUFF(YourColumn,1,NULLIF(CHARINDEX('text',YourColumn),0)+5,'') AS PONumber
FROM dbo.YourTable;

---

Edit: Based on the latest version, then it's not 'text' it's 'Fern Flower' and then you just need the left most characters to the next space (or end of the value?):

SELECT YT.YourColumn,
       LEFT(STUFF(YT.YourColumn,1,CI1.I-1,''),CI2.I - CI1.I) AS PONumber
FROM dbo.YourTable YT
     CROSS APPLY (VALUES(NULLIF(CHARINDEX('Fern Flower',YT.YourColumn),0)+LEN('Fern Flower') + 1))CI1(I)
     CROSS APPLY (VALUES(ISNULL(NULLIF(CHARINDEX(' ',YT.YourColumn,CI1.I),0),LEN(YT.YourColumn))))CI2(I);

db<>fiddle

Answer 2

These types of situations are tricky and can be a real bear to wrestle with.

My first note is to consider adding a PONumber column to your data and capturing that upon insert vs parsing text. Having said that, here's an idea to address your current need.

First, here's a function designed to parse your "fern" po number from a text value:

CREATE FUNCTION dbo.GetPO (
    @text varchar(8000)
)
RETURNS varchar(255)
WITH RETURNS NULL ON NULL INPUT
AS
BEGIN

    DECLARE 
        @pos int = CHARINDEX ( 'fern', @text ),
        @po varchar(255);

    IF @pos > 0 BEGIN

        -- Locate the starting position of the first numeric value.
        -- Ass-u-mes *any* numeric value following the word "fern" is the expected po.

        WHILE ISNUMERIC ( SUBSTRING ( @text, @pos, 1 ) ) = 0 AND @pos <= LEN ( @text )
            SET @pos = @pos + 1;

        -- If @pos is not equal to @text's length then assume a @po value was found. 
        
        IF @pos < LEN ( @text ) BEGIN

            WHILE ISNUMERIC ( SUBSTRING ( @text, @pos, 1 ) ) = 1 BEGIN
                
                SET @po = ISNULL ( @po, '' ) + SUBSTRING ( @text, @pos, 1 );
                SET @pos = @pos + 1;

            END

        END

    END

    RETURN @po;

END
GO

Running SELECT dbo.GetPO ( 'Fern Flower 12345678 More text' ); returns 12345678 .

Next, to continue your previous PONumber in the event GetPO returned NULL , here is an example how you might go about that using dbo.GetPO :

DECLARE @Data table ( [Text] varchar(8000), RowKey int IDENTITY (1,1) );
INSERT INTO @Data VALUES
    ( 'Fern Flower 12345678  More text' ),
    ( '.' ),
    ( '.' ),
    ( 'Fern Flower 23456789 More text' ),
    ( '.' );

;WITH cte AS (
    
    SELECT
        RowKey,
        [Text],
        dbo.GetPO ( [Text] ) AS PONumber
    FROM @Data

)
SELECT
    RowKey,
    [Text],
    CASE
        WHEN PONumber IS NULL THEN (
            -- Get the most recent non-null PONumber.
            SELECT TOP 1 PONumber FROM cte AS x WHERE x.RowKey < cte.RowKey AND x.PONumber IS NOT NULL ORDER BY x.RowKey DESC
        )
        ELSE PONumber -- Keep the existing PONumber.
    END AS PONumber
FROM cte
ORDER BY RowKey;

Returns

+--------+---------------------------------+----------+
| RowKey |              Text               | PONumber |
+--------+---------------------------------+----------+
|      1 | Fern Flower 12345678  More text | 12345678 |
|      2 | .                               | 12345678 |
|      3 | .                               | 12345678 |
|      4 | Fern Flower 23456789 More text  | 23456789 |
|      5 | .                               | 23456789 |
+--------+---------------------------------+----------+

UPDATE

Here's an example of continuing your PONumber across NULL values using a combination of my and @Larnu's examples:

;WITH cte AS (
    
    SELECT
        RowKey,
        [Text],
        LEFT( STUFF( YT.[Text], 1, CI1.I-1, '' ), CI2.I - CI1.I ) AS PONumber
    FROM @Data YT
    CROSS APPLY (
        VALUES ( NULLIF ( CHARINDEX ( 'Fern Flower', YT.[Text] ), 0 ) + LEN ( 'Fern Flower' ) + 1 )
    ) CI1 ( I )
    CROSS APPLY (
        VALUES ( ISNULL ( NULLIF ( CHARINDEX ( ' ', YT.[Text], CI1.I ), 0 ), LEN ( YT.[Text] ) ) )
    ) CI2 ( I )

)
SELECT
    RowKey,
    [Text],
    CASE
        WHEN PONumber IS NULL THEN (
            -- Get the most recent non-null PONumber.
            SELECT TOP 1 PONumber FROM cte AS x WHERE x.RowKey < cte.RowKey AND x.PONumber IS NOT NULL ORDER BY x.RowKey DESC
        )
        ELSE PONumber -- Keep the existing PONumber.
    END AS PONumber
FROM cte
ORDER BY RowKey;

Returns

+--------+---------------------------------+----------+
| RowKey |              Text               | PONumber |
+--------+---------------------------------+----------+
|      1 | Fern Flower 12345678  More text | 12345678 |
|      2 | .                               | 12345678 |
|      3 | .                               | 12345678 |
|      4 | Fern Flower 23456789 More text  | 23456789 |
|      5 | .                               | 23456789 |
+--------+---------------------------------+----------+