Udtræk efternavn, fornavn og suffiks i separate kolonner

Du bør virkelig gemme disse dele af navnet i separate kolonner (første normal form) for at undgå en sådan parsing.

Du kan lægge al logikken ind i et stort kald af indlejrede funktioner, men det er ret praktisk at adskille dem i enkelte kald ved hjælp af CROSS APPLY .

Parsingen er ligetil:

• find kommaposition
• opdel strengen i en del før komma (LastName ) og delen AfterComma
• find placeringen af ​​det første mellemrum i den anden del AfterComma
• opdeler strengen i to dele igen - dette giver FirstName og resten (AfterSpace )
• find pladsens position i AfterSpace
• opdeler strengen i to dele igen - dette giver Initial og Suffix .

Forespørgslen kontrollerer også resultaterne af CHARINDEX - den returnerer 0, hvis strengen ikke findes.

Det er klart, at hvis strengværdien ikke er i det forventede format, får du et forkert resultat.

DECLARE @T TABLE (Name varchar(8000));
INSERT INTO @T (Name) VALUES
('Walker'),
('Walker,James M JR'),
('Smith,Jack P'),
('Smith,Whitney');

SELECT
    Name
    ,LastName
    ,AfterComma
    ,FirstName
    ,AfterSpace
    ,MidInitial
    ,Suffix
FROM
    @T
    CROSS APPLY (SELECT CHARINDEX(',', Name) AS CommaPosition) AS CA_CP
    CROSS APPLY (SELECT CASE WHEN CommaPosition > 0 THEN 
        LEFT(Name, CommaPosition - 1) ELSE Name END AS LastName) AS CA_LN
    CROSS APPLY (SELECT CASE WHEN CommaPosition > 0 THEN 
        SUBSTRING(Name, CommaPosition + 1, 8000) ELSE '' END AS AfterComma) AS CA_AC

    CROSS APPLY (SELECT CHARINDEX(' ', AfterComma) AS SpacePosition) AS CA_SP
    CROSS APPLY (SELECT CASE WHEN SpacePosition > 0 THEN 
        LEFT(AfterComma, SpacePosition - 1) ELSE AfterComma END AS FirstName) AS CA_FN
    CROSS APPLY (SELECT CASE WHEN SpacePosition > 0 THEN 
        SUBSTRING(AfterComma, SpacePosition + 1, 8000) ELSE '' END AS AfterSpace) AS CA_AS

    CROSS APPLY (SELECT CHARINDEX(' ', AfterSpace) AS Space2Position) AS CA_S2P
    CROSS APPLY (SELECT CASE WHEN Space2Position > 0 THEN 
        LEFT(AfterSpace, Space2Position - 1) ELSE AfterSpace END AS MidInitial) AS CA_MI
    CROSS APPLY (SELECT CASE WHEN Space2Position > 0 THEN 
        SUBSTRING(AfterSpace, Space2Position + 1, 8000) ELSE '' END AS Suffix) AS CA_S

resultat

Name                 LastName    AfterComma    FirstName    AfterSpace  MidInitial  Suffix
Walker               Walker
Walker,James M JR    Walker      James M JR    James        M JR        M           JR
Smith,Jack P         Smith       Jack P        Jack         P           P
Smith,Whitney        Smith       Whitney       Whitney