在具有 where 条件的空表上返回右外连接的结果答案

【问题标题】：Return Results on Right Outer Join on empty table with where condtion在具有 where 条件的空表上返回右外连接的结果
【发布时间】：2015-11-04 04:38:42
【问题描述】：

所以我试图从billing_monthly_verizon_charges_detail_archive 返回 12 个月的数据，但如果没有删除条件 verizon.ITEM_DESCRIPTION <> 'Payment Received'，我无法找到在没有数据的情况下返回 0 的方法。我明白为什么它没有返回任何数据，但我怎样才能让它在每个月份都返回 0 invoice_date table 并带有条件 - 这是有数据时需要的。

SELECT 'H. Verizon' AS category, CONVERT(VARCHAR(7), id.INVOICE_DATE, 111) AS invoice_date, ISNULL(SUM(verizon.COST), 0.00) AS total_charges
FROM BILLING_MONTHLY_VERIZON_CHARGES_DETAIL_ARCHIVE AS verizon 
RIGHT OUTER JOIN
INVOICE_DATES AS id ON verizon.BILL_CYCLE_DATE = id.INVOICE_DATE
WHERE(id.INVOICE_DATE BETWEEN @BillingMonthMinus13 AND @BillingMonth) AND (verizon.ITEM_DESCRIPTION <> 'Payment Received')
GROUP BY id.INVOICE_DATE

【问题讨论】：

wiki.lessthandot.com/index.php/WHERE_conditions_on_a_LEFT_JOIN

标签： tsql conditional-statements outer-join

【解决方案1】：

COALESCE(verizon.ITEM_DESCRIPTION,'') <> 'Payment Received'

【讨论】：

【解决方案2】：

考虑：

SELECT  
    'H. Verizon' AS category, 
    CONVERT(VARCHAR(7), INVOICE_DATE,111) AS invoice_date, 
    ISNULL(SUM(COST), 0.00) AS total_charges
FROM 
    (SELECT 
        INVOICE_DATE
    FROM
        INVOICE_DATES 
    WHERE
        INVOICE_DATE BETWEEN @BillingMonthMinus13 AND @BillingMonth ) id    LEFT OUTER JOIN
    (SELECT
        BILL_CYCLE_DATE, 
        COST
    FROM
        BILLING_MONTHLY_VERIZON_CHARGES_DETAIL_ARCHIVE
    WHERE
        ITEM_DESCRIPTION <> 'Payment Received'  ) verizon   ON 
    BILL_CYCLE_DATE = INVOICE_DATE
GROUP BY 
    INVOICE_DATE

【讨论】：