返回左表连接的所有结果，以及右表可以填写的缺失行

Question

我有一个问题，我试图从一个表中返回所有行，同时用另一个表填充数据空白（如果它存在）。目前我有工作SQL，这是一个简单的例子来展示我在做什么。

SELECT    a.timestamp, 
          number 
FROM      tablea a WITH (nolock) 
UNION 
SELECT     b.timestamp, 
           number 
FROM       tablea a WITH (nolock) 
RIGHT JOIN tableb b WITH (nolock) 
ON         a.timestamp = b.timestamp 
WHERE      a.timestamp IS NULL

通过一些示例数据，这会产生这个结果，这就是我想要的。 （抱歉格式化）

| TableA |                    | TableB |               | Result |
| 2017-7-24 | 1 |             | 2017-7-24 | 2 |        | 2017-7-24 | 1 |
| 2017-7-26 | 2 |             | 2017-7-25 | 3 |        | 2017-7-25 | 3 |
| 2017-7-27 | 2 |             | 2017-7-27 | 6 |        | 2017-7-26 | 2 |
                                                       | 2017-7-27 | 2 |

这样就可以了，我只是想知道是否有不同的方法可以产生预期的结果？

Answer 1

SELECT * FROM TAbleA
UNION ALL
SELECT * FROM TableB b
WHERE NOT EXISTS (
   SELECT * FROM TableA a
   WHERE a.timestamp = b.timestamp

）

SELECT * FROM TableA
UNION ALL
SELECT * FROM TableB
WHERE timestamp NOT IN (
   SELECT timestamp FROM TableA
)

Answer 2

<tbody> <!-- ngRepeat: lineItem in paymentDetails.responseObject[0].schedules[0].schedule_line_items track by $index --> <tr class="ng-scope" ng-repeat="lineItem in paymentDetails.responseObject[0].schedules[0].schedule_line_items track by $index"> <td class="ng-binding">Jul 27, 2017</td> <td> <td class="ng-binding">$45.00</td> <!-- ngIf: paymentDetails.responseObject[0].fee_amount > 0 --> <td class="ng-binding ng-scope" ng-if="paymentDetails.responseObject[0].fee_amount > 0">$0.90</td> <!-- end ngIf: paymentDetails.responseObject[0].fee_amount > 0 --> <td> <td class="" ng-switch="" on="lineItem.statusString" ng-show="lineItem.statusString" style=""> <td class="ng-binding ng-hide" ng-show="!lineItem.statusString" ng-bind-html="receiptTemplate.ready" style="">Ready</td> <td class="ng-binding" ng-show="lineItem.authorizationString" ng-bind-html="lineItem.authorizationString" style="">53433 Bogus Gateway: Forced success</td> <td class="ng-hide" ng-show="!lineItem.authorizationString" style=""/> <td> </tr> 结果将为您提供更清晰（可能更有效）的查询：

coalesce

Answer 3

SELECT * FROM TableA 
UNION
SELECT * FROM TableB
WHERE timestamp NOT IN (SELECT timestamp FROM TableA)