Zjednodušenie dotaz s vnorené dopyt

Question 1

Chcem odstrániť potrebu vnorené dotaz, či môžem z môjho dotazu nižšie, ale ja som snaží zistiť ako.

Toto je schéma:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE IF NOT EXISTS [dbo].[expiration]
(
    [batch_number] [int] NOT NULL,
    [fruit_number] [int] NOT NULL,
    [store_number] [int] NOT NULL,
    [expiration_date] [date] NULL
) ON [PRIMARY]

CREATE TABLE IF NOT EXISTS [dbo].[fruits]
(
    [fruit_number] [int] NOT NULL,
    [fruit_name] [nvarchar](50) NOT NULL
) ON [PRIMARY]

Je to údaje:

INSERT IGNORE INTO [dbo].[expiration] ([batch_number], [fruit_number], [store_number], [expiration_date]) 
VALUES (1, 3, 4, CAST(N'2021-11-25' AS Date))

INSERT IGNORE INTO [dbo].[expiration] ([batch_number], [fruit_number], [store_number], [expiration_date]) 
VALUES (1, 2, 2, CAST(N'2021-11-22' AS Date))

INSERT IGNORE INTO [dbo].[expiration] ([batch_number], [fruit_number], [store_number], [expiration_date]) 
VALUES (1, 5, 3, CAST(N'2021-11-30' AS Date))

INSERT IGNORE INTO [dbo].[expiration] ([batch_number], [fruit_number], [store_number], [expiration_date]) 
VALUES (2, 2, 7, NULL)

INSERT IGNORE INTO [dbo].[expiration] ([batch_number], [fruit_number], [store_number], [expiration_date]) 
VALUES (2, 3, 2, CAST(N'2021-12-12' AS Date))

INSERT IGNORE INTO [dbo].[expiration] ([batch_number], [fruit_number], [store_number], [expiration_date]) 
VALUES (1, 1, 5, NULL)

INSERT IGNORE INTO [dbo].[expiration] ([batch_number], [fruit_number], [store_number], [expiration_date]) 
VALUES (2, 1, 6, CAST(N'2021-11-28' AS Date))

INSERT IGNORE INTO [dbo].[fruits] ([fruit_number], [fruit_name]) 
VALUES (1, N'banana')

INSERT IGNORE INTO [dbo].[fruits] ([fruit_number], [fruit_name]) 
VALUES (2, N'apple')

INSERT IGNORE INTO [dbo].[fruits] ([fruit_number], [fruit_name]) 
VALUES (3, N'pear')

INSERT IGNORE INTO [dbo].[fruits] ([fruit_number], [fruit_name]) 
VALUES (4, N'peach')

INSERT IGNORE INTO [dbo].[fruits] ([fruit_number], [fruit_name]) 
VALUES (5, N'strawberry')

A toto je môj dotaz:

SELECT
    fruit_number, 
    MAX(expirationDate) as expirationDate
FROM
    (SELECT
        f.fruit_number,
        CASE
            WHEN e.expiration_date is NULL AND e.fruit_number IS NOT NULL THEN 1
            ELSE 0
        END AS expirationDate
    FROM
        expiration AS e
    FULL OUTER JOIN 
        fruits AS f ON f.fruit_number = e.fruit_number
    WHERE
        f.fruit_number IS NOT NULL) t
GROUP BY
    fruit_number
ORDER BY
    fruit_number

To produkuje tento výsledok:

fruit_number	expirationDate
1	1
2	1
3	0
4	0
5	0

Na resultset je to, čo som po, ale je to škaredé so vnorené dotaz. Je to možné urobiť bez vnorených dotaz? Online query analyzer (https://www.eversql.com/sql-query-optimizer/) povedal, aby move sub-dopyt do temp tabuľka dotazu proti tomu, ale nie je len robiť rovnakú vec na ďalšie kroky?

Question 2

Prvá zmena by som, aby sa so svojimi spája. Nemá zmysel používať FULL OUTER JOIN potom dal v ak klauzula, ktorá hovorí, f.fruit_number IS NOT NULL. To znamená, že každý riadok musí mať záznam v fruits,, takže váš dopyt by väčší zmysel, ako SELECT .. FROM fruits AS f LEFT JOIN expiration AS e ON e.fruit_number = f.fruit_number.

Môžete tiež odstrániť poddotaz umiestnením vašom prípade prejavu priamo v MAX funkcia:

SELECT  f.fruit_number, 
        f.fruit_name,
        expirationDate = MAX(CASE WHEN e.expiration_date IS NULL 
                                    AND e.fruit_number IS NOT NULL THEN 1 ELSE 0 END)
FROM    dbo.fruits AS f
        LEFT JOIN dbo.expiration AS e
            ON e.fruit_number = f.fruit_number
GROUP BY f.fruit_number, f.fruit_name
ORDER BY f.fruit_number;

Príklad na db - <>husle

Question 3

Daj to vyskúšať, som presvedčený, že dostane to, čo si chcel:

SELECT t1.fruit_number
, CASE WHEN MIN(ISNULL(expiration_date, '1/1/1900')) = CAST('1/1/1900' as date) and t2.fruit_number IS NOT NULL THEN 1 ELSE 0 END expirationDate
FROM fruits t1 
LEFT JOIN expiration t2 on t1.fruit_number = t2.fruit_number
GROUP BY t1.fruit_number, t2.fruit_number
ORDER BY t1.fruit_number

Question 4

Zdá sa, že ste overcomplicating to. Za predpokladu, že fruit_number je jedinečný v fruitsnie je potrebné pre group bynamiesto používania exists

SELECT
  f.fruit_number, 
  f.fruit_name,
  expirationDate = CASE WHEN EXISTS (SELECT 1
                       FROM dbo.expiration AS e
                       WHERE e.fruit_number = f.fruit_number
                         AND e.expiration_date IS NULL
                     ) THEN 1 ELSE 0 END
FROM dbo.fruits AS f
ORDER BY f.fruit_number;

db - <>husle

GarethD · Answer 1 · 2021-11-23T12:35:52

Prvá zmena by som, aby sa so svojimi spája. Nemá zmysel používať FULL OUTER JOIN potom dal v ak klauzula, ktorá hovorí, f.fruit_number IS NOT NULL. To znamená, že každý riadok musí mať záznam v fruits,, takže váš dopyt by väčší zmysel, ako SELECT .. FROM fruits AS f LEFT JOIN expiration AS e ON e.fruit_number = f.fruit_number.

Môžete tiež odstrániť poddotaz umiestnením vašom prípade prejavu priamo v MAX funkcia:

SELECT  f.fruit_number, 
        f.fruit_name,
        expirationDate = MAX(CASE WHEN e.expiration_date IS NULL 
                                    AND e.fruit_number IS NOT NULL THEN 1 ELSE 0 END)
FROM    dbo.fruits AS f
        LEFT JOIN dbo.expiration AS e
            ON e.fruit_number = f.fruit_number
GROUP BY f.fruit_number, f.fruit_name
ORDER BY f.fruit_number;

Príklad na db - <>husle

JMabee · Answer 2 · 2021-11-23T12:24:55

Daj to vyskúšať, som presvedčený, že dostane to, čo si chcel:

SELECT t1.fruit_number
, CASE WHEN MIN(ISNULL(expiration_date, '1/1/1900')) = CAST('1/1/1900' as date) and t2.fruit_number IS NOT NULL THEN 1 ELSE 0 END expirationDate
FROM fruits t1 
LEFT JOIN expiration t2 on t1.fruit_number = t2.fruit_number
GROUP BY t1.fruit_number, t2.fruit_number
ORDER BY t1.fruit_number

Charlieface · Answer 3 · 2021-11-23T16:39:29

Zdá sa, že ste overcomplicating to. Za predpokladu, že fruit_number je jedinečný v fruitsnie je potrebné pre group bynamiesto používania exists

SELECT
  f.fruit_number, 
  f.fruit_name,
  expirationDate = CASE WHEN EXISTS (SELECT 1
                       FROM dbo.expiration AS e
                       WHERE e.fruit_number = f.fruit_number
                         AND e.expiration_date IS NULL
                     ) THEN 1 ELSE 0 END
FROM dbo.fruits AS f
ORDER BY f.fruit_number;

db - <>husle

Zjednodušenie dotaz s vnorené dopyt

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