SQL Switch / Case in 'waar' klousule

Question

Ek het probeer soek rond, maar ek kon niks wat my sal help om uit te vind.

Ek probeer om dit te doen in SQL:

declare @locationType varchar(50);
declare @locationID int;

SELECT column1, column2
FROM viewWhatever
WHERE
CASE @locationType
    WHEN 'location' THEN account_location = @locationID
    WHEN 'area' THEN xxx_location_area = @locationID
    WHEN 'division' THEN xxx_location_division = @locationID

Ek weet dat Ek nie sou hê om '= @locationID' aan die einde van elke een te sit, maar ek kan die sintaksis selfs naby aan korrek nie. SQL hou kla oor my '=' op die eerste WANNEER lyn ...

Hoe kan ek dit doen?

Answer 1

declare @locationType varchar(50);
declare @locationID int;

SELECT column1, column2
FROM viewWhatever
WHERE
@locationID = 
  CASE @locationType
      WHEN 'location' THEN account_location
      WHEN 'area' THEN xxx_location_area 
      WHEN 'division' THEN xxx_location_division 
  END

Answer 2

sonder 'n case-stelling ...

SELECT column1, column2
FROM viewWhatever
WHERE
    (@locationType = 'location' AND account_location = @locationID)
    OR
    (@locationType = 'area' AND xxx_location_area = @locationID)
    OR
    (@locationType = 'division' AND xxx_location_division = @locationID)

Answer 3

Hier kan jy gaan.

SELECT
   column1, 
   column2
FROM
   viewWhatever
WHERE
CASE 
    WHEN @locationType = 'location' AND account_location = @locationID THEN 1
    WHEN @locationType = 'area' AND xxx_location_area = @locationID THEN 1
    WHEN @locationType = 'division' AND xxx_location_division = @locationID THEN 1
    ELSE 0
END = 1

Answer 4

Ek sou sê dit is 'n aanduiding van 'n gebrekkige tafel struktuur. Miskien is die ander plek tipes moet geskei word in verskillende tafels, sodat jy baie ryker bevraagteken doen en ook verhoed dat onnodige kolomme rondom.

As jy nie in staat is om die struktuur te verander is, iets soos die onderstaande kan werk:

SELECT
    *
FROM
    Test
WHERE
    Account_Location = (
        CASE LocationType
          WHEN 'location' THEN @locationID
          ELSE Account_Location
        END
    )
    AND
    Account_Location_Area = (
        CASE LocationType
          WHEN 'area' THEN @locationID
          ELSE Account_Location_Area
        END
    )

En dies meer ... Ons kan nie die struktuur van die vraag op die vlieg te verander, maar ons kan dit ignoreer deur die predicaten gelyk hulself uit.

EDIT: Bogenoemde voorstelle is natuurlik baie beter, net ignoreer myn

.

Answer 5

Die probleem met hierdie is dat wanneer die SQL-enjin gaan na die uitdrukking te evalueer, dit gaan die VANAF gedeelte aan die behoorlike tafels trek, en dan die WAAR gedeelte om 'n paar basis kriteria voorsien, so dit kan nie behoorlik 'n dinamiese toestand op te evalueer watter kolom om seker te maak teen.

Jy kan 'n WHERE klousule gebruik wanneer jy die beheer van die WAAR kriteria in die gesegde, soos

WHERE account_location = CASE @locationType
                              WHEN 'business' THEN 45
                              WHEN 'area' THEN 52
                         END

so in jou spesifieke geval, jy gaan nodig het die navraag in 'n gestoor proses of skep drie afsonderlike navrae.

Answer 6

OR operateur kan wees alternatief van geval toe in waar toestand

ALTER PROCEDURE [dbo].[RPT_340bClinicDrugInventorySummary]
    -- Add the parameters for the stored procedure here
     @ClinicId BIGINT = 0,
     @selecttype int,
     @selectedValue varchar (50)
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
SELECT
    drugstock_drugname.n_cur_bal,drugname.cdrugname,clinic.cclinicname

FROM drugstock_drugname
INNER JOIN drugname ON drugstock_drugname.drugnameid_FK = drugname.drugnameid_PK
INNER JOIN drugstock_drugndc ON drugname.drugnameid_PK = drugstock_drugndc.drugnameid_FK
INNER JOIN drugndc ON drugstock_drugndc.drugndcid_FK = drugndc.drugid_PK
LEFT JOIN clinic ON drugstock_drugname.clinicid_FK = clinic.clinicid_PK

WHERE   (@ClinicId = 0 AND 1 = 1)
    OR  (@ClinicId != 0 AND drugstock_drugname.clinicid_FK = @ClinicId)

    -- Alternative Case When You can use OR
    AND ((@selecttype = 1 AND 1 = 1)
    OR  (@selecttype = 2 AND drugname.drugnameid_PK = @selectedValue)
    OR  (@selecttype = 3 AND drugndc.drugid_PK = @selectedValue)
    OR  (@selecttype = 4 AND drugname.cdrugclass = 'C2')
    OR  (@selecttype = 5 AND LEFT(drugname.cdrugclass, 1) = 'C'))

ORDER BY clinic.cclinicname, drugname.cdrugname
END

Answer 7

Probeer asseblief hierdie navraag. Antwoord op bogenoemde post:

select @msgID, account_id
    from viewMailAccountsHeirachy
    where 
    CASE @smartLocationType
        WHEN 'store' THEN account_location
        WHEN 'area' THEN xxx_location_area 
        WHEN 'division' THEN xxx_location_division 
        WHEN 'company' THEN xxx_location_company 
    END  = @smartLocation

Answer 8

Probeer hierdie:

WHERE (
    @smartLocationType IS NULL 
    OR account_location = (
         CASE
            WHEN @smartLocationType IS NOT NULL 
                 THEN @smartLocationType
            ELSE account_location 
         END
    )
)

Answer 9

Case Statement in SQL Server Example

Syntax

CASE [ expression ]

   WHEN condition_1 THEN result_1
   WHEN condition_2 THEN result_2
   ...
   WHEN condition_n THEN result_n

   ELSE result

END

Example

SELECT contact_id,
CASE website_id
  WHEN 1 THEN 'TechOnTheNet.com'
  WHEN 2 THEN 'CheckYourMath.com'
  ELSE 'BigActivities.com'
END
FROM contacts;

OR

SELECT contact_id,
CASE
  WHEN website_id = 1 THEN 'TechOnTheNet.com'
  WHEN website_id = 2 THEN 'CheckYourMath.com'
  ELSE 'BigActivities.com'
END
FROM contacts;

Answer 10

Probeer hierdie navraag. Sy baie maklik om te verstaan:

CREATE TABLE PersonsDetail(FirstName nvarchar(20), LastName nvarchar(20), GenderID int);
GO

INSERT INTO PersonsDetail VALUES(N'Gourav', N'Bhatia', 2),
              (N'Ramesh', N'Kumar', 1),
              (N'Ram', N'Lal', 2),
              (N'Sunil', N'Kumar', 3),
              (N'Sunny', N'Sehgal', 1),
              (N'Malkeet', N'Shaoul', 3),
              (N'Jassy', N'Sohal', 2);
GO

SELECT FirstName, LastName, Gender =
    CASE GenderID
    WHEN 1 THEN 'Male'
    WHEN 2 THEN 'Female'
    ELSE 'Unknown'
    END
FROM PersonsDetail