如何編寫多連接SQL查詢並獲取查詢結果，即使1個表缺少的連接排

Question

我有以下查詢語句：

$query_string = ' 
    SELECT customerID, lastName, firstName, companyName, email, citizenship, primaryLanguage 
    FROM customers 
    JOIN citizenships USING(citizenshipID) 
    JOIN languages USING(languageID) 
    JOIN paymentMethods USING(customerID) 
    WHERE customerID = "1" 
'; 

目前的客戶，公民和語言表的每個包含行和正確加入。我的查詢結果爲客戶＃1返回1行。

paymentMethods表中目前不包含任何行。當我將paymentMethods的連接語法添加到查詢字符串時，我的查詢結果爲客戶＃1返回0行。

我想加入paymentMethods，並且只有在paymentMethods表存在時才返回一行，否則不會返回任何客戶行。

我該如何調整我的JOIN語法才能實現？

謝謝。

Answer 1

與LEFT JOIN替換爲：

SELECT customerID, lastName, firstName, companyName, email, citizenship, primaryLanguage 
FROM customers 
JOIN citizenships 
USING (citizenshipID) 
JOIN languages 
USING (languageID) 
LEFT JOIN 
     paymentMethods 
USING (customerID) 
WHERE customerID = "1" 

Answer 2

$query_string = ' 
    SELECT customerID, lastName, firstName, companyName, email, citizenship, primaryLanguage 
    FROM customers 
    JOIN citizenships USING(citizenshipID) 
    JOIN languages USING(primaryLanguageID) 
    LEFT JOIN paymentMethids USING(customerID) 
    WHERE customerID = "1" 
';