選択と異なる値の複数の行を挿入

Question

私は以下のテーブルProjectsとProjectFieldsを持っています。私は別の値に加えて、いくつかの他の値との1、この方法を移入しようとしています：

INSERT INTO "ProjectFields" ("projectId", name, type, "isDefault") 
     (SELECT "projectId", 'Notes', 'textarea', true FROM "Projects"), -- creates one field called 'Notes' for every project. 
     (SELECT "projectId", 'Bio', 'textarea', true FROM "Projects"), -- creates one field called 'Bio' for every project. 
     (SELECT "projectId", 'Photo', 'text', true FROM "Projects"); -- creates one field called 'Photo' for every project. 

アイデアは、すべてのプロジェクトがProjectFieldsテーブルで3つの参照フィールドを持たなければならないということです。上記のコードはうまくいきませんが、PostgreSQLを使ってこれを行う方法はありますか？

あなたが良いアイデアをお持ちでしたら、教えてください、ありがとうございます。

Answer 1

あなたはほぼそこにいます！ただ、出来上がりUNIONとを使用します。

INSERT INTO "ProjectFields" ("projectId", name, type, "isDefault") 
     SELECT "projectId", 'Notes', 'textarea', true FROM "Projects" 
     UNION ALL 
     SELECT "projectId", 'Bio', 'textarea', true FROM "Projects" 
     UNION ALL 
     SELECT "projectId", 'Photo', 'text', true FROM "Projects"; 

--As you asked, using only one SELECT on Projects (but using a CTE) 
--But I didn't recommend this solution, why increase complexity of a query just to avoid the 3 SELECTS? 
INSERT INTO "ProjectFields" ("projectId", name, "isDefault") 
    WITH tmp (proj_id, field_name, is_default) AS (  
     SELECT "projectId", UNNEST(ARRAY['Notes','Bio', 'Photo']), true FROM "Projects" 
    ) 
    SELECT proj_id, field_name, CASE field_name WHEN 'Notes' THEN 'textarea' WHEN 'Bio' THEN 'textarea' ELSE 'text' END,is_default FROM tmp; 

--Or perhaps in a more cleaner way as stated by @Marth: 
INSERT INTO "ProjectFields" ("projectId", name, "isDefault") 
    SELECT * FROM projects, (VALUES ('notes', 'textarea'), ('bio', 'textarea'), ('Photo', 'text')) AS t(name, "type");