內部加入null id選擇行

-1

我們有兩個表格，一個帶有ids和一個帶有名稱。有些ID是不需要（可以爲空），例如：內部加入null id選擇行

rowId item1Id, item2Id, item3Id (item3Id can be null)

後，我們加入這個兩個表，我們得到的ID和名稱。但是，如果item3 Id爲null，則不顯示該行。

一些數據：

表1

ROWID，item1Id，item2Id，item3Id

1，2，3，4

2，1,5，NULL

在我們的案例中，我們得到一行結果（1行）

所以，如果它是空的，它不存在於表2中，並且行未顯示，但我們想要顯示空值。所以當我們離開連接這兩個表時，結果應該有2行。

這是SQL：

SELECT Recipes.recipeId, Recipes.userId,Users.firstName + ' ' + Users.lastName as userName, servingTypeId, 
Codings.coding as servingType, categoryId, Codings_2.coding as healthAspects, continentId, 
Codings_3.coding as continent, countryId, CodingsAssociated.coding as country, typeOfPreparationId, 
Codings_4.coding as typeOfPreparation, flavourId, Codings_5.coding as flavour, preparationSkillId, 
Codings_6.coding as preparationSkill, seasonId, activePreparationTime, 
overallPreparationTime, isLocalDelight, servings, Codings_7.coding as season , 
calories, youTubeId, datePosted, isComposite, Recipes.isApproved, Recipes.timestamp, title, 
localDelightRegion, otherFeatures, cookingInstructions 
     FROM Recipes LEFT OUTER JOIN 

     Codings ON Recipes.servingTypeId = Codings.codingKeyId LEFT OUTER JOIN 
     Codings as Codings_2 ON Recipes.categoryId = Codings_2.codingKeyId LEFT OUTER JOIN 
     Codings as Codings_3 ON Recipes.continentId = Codings_3.codingKeyId LEFT OUTER JOIN 
     CodingsAssociated ON Recipes.countryId = CodingsAssociated.codingKeyId LEFT OUTER JOIN 
     Codings as Codings_4 ON Recipes.typeOfPreparationId = Codings_4.codingKeyId LEFT OUTER JOIN 
     Codings as Codings_5 ON Recipes.flavourId = Codings_5.codingKeyId LEFT OUTER JOIN 
     Codings as Codings_6 ON Recipes.preparationSkillId = Codings_6.codingKeyId LEFT OUTER JOIN 
     Codings as Codings_7 ON Recipes.seasonId = Codings_7.codingKeyId LEFT OUTER JOIN 
     RecipesTranslations ON Recipes.recipeId = RecipesTranslations.recipeId LEFT OUTER JOIN 
     Users ON Recipes.userId = Users.userId 

     WHERE CodingsAssociated.languageId = @languageId AND Codings.languageId = @languageId 
     AND Codings_2.languageId = @languageId AND Codings_3.languageId = @languageId 
     AND Codings_4.languageId = @languageId AND 
     Codings_5.languageId = @languageId AND Codings_6.languageId = @languageId AND RecipesTranslations.languageId = @languageId 
     AND Codings_7.languageId = @languageId

例如因爲seasonId有時是空未顯示爲加盟Codings_7.coding，但我不會像也顯示這些行，其中ID是空的名字也是空的。

來源

2012-09-07 janilemy

你的問題是什麼？ – xdazz

左連接將做你想要的。但是，如果你過濾table2列上的表格，你將有效地恢復到內部連接。所有這些過濾器都應該移至ON子句。 –

很難說這裏有什麼問題，但我想你需要做一個外連接，並且從tsql標記我猜你使用MS SQL服務器，所以在這裏你去：http://msdn.microsoft。 com/en-us/library/aa213228（v = sql.80）.aspx – bpgergo

如前所述通過Nikola Markovinović你需要的地方條件移動到連接條件

這裏您選擇更正：

SELECT 
    Recipes.recipeId, 
    Recipes.userId, 
    --- 
    cookingInstructions 
FROM 
    Recipes 
    LEFT OUTER JOIN Codings ON 
     Recipes.servingTypeId = Codings.codingKeyId AND 
     Codings.languageId = @languageId 
    LEFT OUTER JOIN Codings as Codings_2 ON 
     Recipes.categoryId = Codings_2.codingKeyId AND 
     Codings_2.languageId = @languageId 
    LEFT OUTER JOIN Codings as Codings_3 ON 
     Recipes.continentId = Codings_3.codingKeyId AND 
     Codings_3.languageId = @languageId 
    LEFT OUTER JOIN CodingsAssociated ON 
     Recipes.countryId = CodingsAssociated.codingKeyId AND 
     CodingsAssociated.languageId = @languageId 
    LEFT OUTER JOIN Codings as Codings_4 ON 
     Recipes.typeOfPreparationId = Codings_4.codingKeyId AND 
     Codings_4.languageId = @languageId 
    LEFT OUTER JOIN Codings as Codings_5 ON 
     Recipes.flavourId = Codings_5.codingKeyId AND 
     Codings_5.languageId = @languageId 
    LEFT OUTER JOIN Codings as Codings_6 ON 
     Recipes.preparationSkillId = Codings_6.codingKeyId AND 
     Codings_6.languageId = @languageId 
    LEFT OUTER JOIN Codings as Codings_7 ON 
     Recipes.seasonId = Codings_7.codingKeyId AND 
     Codings_7.languageId = @languageId 
    LEFT OUTER JOIN RecipesTranslations ON 
     Recipes.recipeId = RecipesTranslations.recipeId AND 
     RecipesTranslations.languageId = @languageId 
    LEFT OUTER JOIN Users ON 
     Recipes.userId = Users.userId ;

來源

2012-09-07 13:52:40

這很難說，正在這裏問什麼，但我想你需要做的外連接，並從TSQL的標籤，我想你用MS SQL服務器，所以在這裏你去：http://msdn.microsoft.com/en-us/library/aa213228(v=sql.80).aspx

例如：

SELECT * 
FROM table1 a LEFT OUTER JOIN table2 b 
ON a.id_to_join_on = b.id_to_join_on

來源

2012-09-07 13:22:41 bpgergo

我嘗試這一點，並改變內部聯接與左外部聯接，但包含seasinId空行，不顯示（如果季節ID爲空，它不能顯示季節，但我希望如果它爲空它也顯示季節名稱空）如果您瞭解 – janilemy

對不起，您發佈的選擇聲明中沒有seasinId，所以我仍然不明白。讓我們嘗試縮小這個問題，只留下兩個表格。那麼哪個表包含'seasionID'和哪個表包含'season_name'？ – bpgergo

內部加入null id選擇行

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