如何處理SQL初學者的多個查詢表？

Question

我很難在多個查找表中纏住我的頭。我有所有的中央表中的各列中的信息，但編號：

db_supply (Main supplier information data table) 
----------------------------------------------- 
| Supplier_ID | Supply_Type_ID | Itm_ID | Stock | 
|-----------------------------------------------| 
| 1   | 1    | 33  | 3  | 
|-----------------------------------------------| 
| 2   | 2    | 28  | 1  | 
----------------------------------------------- 

lookup_supplier 
----------------------------- 
| Supplier_ID | Supplier_Name | 
|-----------------------------| 
| 1   | Walter  | 
|-----------------------------| 
| 2   | Jesse   | 
----------------------------- 

lookup_supply_type 
----------------------------------- 
| Supply_Type_ID | Supply_Type_Name | 
|-----------------------------------| 
| 1    | Import   | 
|-----------------------------------| 
| 2    | Delivery   | 
----------------------------------- 

lookup_itm 
------------------------ 
| Itm_ID | Itm_Name  | 
|------------------------| 
| 33  | Pickles  | 
|------------------------| 
| 28  | Burger  | 
------------------------ 

A query for 'Burger' will output this table: 
----------------------------------------------------- 
| Supplier_Name | Supply_Type_Name | Itm_Name | Stock | 
|-----------------------------------------------------| 
| Jesse   | Delivery   | Burger | 1  | 
----------------------------------------------------- 

我怎麼會真正實現這一目標？到目前爲止，我有：

SELECT * FROM db_supply WHERE Itm_ID = (SELECT Itm_ID FROM lookup_itm WHERE Itm_Name = 'Burger')

這將使我db_supply表的第二行使用標識不擡頭呢。我是否必須嵌套我的選擇來查找多個表？不知道這裏。

Answer 1

SELECT b.Supplier_Name, 
     c.Supply_Type_Name, 
     d.Itm_Name, 
     a.Stock 
FROM db_supply a 
     INNER JOIN lookup_supplier b 
      ON a.Supplier_ID = b.Supplier_ID 
     INNER JOIN lookup_supply_type c 
      ON a.Supply_Type_ID = c.Supply_Type_ID 
     INNER JOIN lookup_itm d 
      ON a.Itm_ID = d.Itm_ID 
WHERE d.Itm_Name = 'Burger' 

• SQLFiddle Demo

爲了進一步獲得更多的知識有關加入，請訪問以下鏈接：

• Visual Representation of SQL Joins

輸出

╔═══════════════╦══════════════════╦══════════╦═══════╗ 
║ SUPPLIER_NAME ║ SUPPLY_TYPE_NAME ║ ITM_NAME ║ STOCK ║ 
╠═══════════════╬══════════════════╬══════════╬═══════╣ 
║ Jesse   ║ Delivery   ║ Burger ║  1 ║ 
╚═══════════════╩══════════════════╩══════════╩═══════╝ 

Answer 2

嘗試以下查詢：

select b.Supplier_Name,c.Supply_Type_Name,d.itemName from db_supply a,lookup_supplier b,lookup_supply_type c,lookup_itm d where a.Supplier_ID=b.Supplier_ID and a.Supply_Type_ID=c.Supply_Type_ID and a.Itm_ID=d.Itm_ID and d.Itm_Name='Burger'