如果右连接没有返回任何行，则mysql设置为null或0

Question

我有以下查询，没有返回任何行。 但是，如果发生这种情况，我想将值设置为0或null。 我该怎么做呢？

UPDATE `hdb`.`projects` 
RIGHT JOIN (
  SELECT jobs.PROJID, round(SUM(jobs.value),2) AS SumOfJobValues, round(Sum(jobs.Earned),2) AS SumOfEarnedValues 
  FROM jobs
  WHERE projects.PROJID = 1312184
  GROUP BY jobs.PROJID
) as temp ON projects.PROJID = temp.PROJID
SET 
  projects.VALUE = round(SumOfJobValues,2), 
  projects.WIP = round(SumOfEarnedValues,2)

我重写了我的查询使用左连接，它在mysql中工作。 然而当我使用PHP Yii框架运行这个我不起作用。

UPDATE `hdb`.`projects` 
left JOIN (
  SELECT 
    jobs.PROJID, 
    round(SUM(jobs.value),2) AS SumOfJobValues,
    round(Sum(jobs.Earned),2) AS SumOfEarnedValues 
  FROM jobs         
  GROUP BY jobs.PROJID
) as temp ON projects.PROJID = temp.PROJID
SET 
  projects.VALUE = round(SumOfJobValues,2), 
  projects.WIP = round(SumOfEarnedValues,2)
WHERE projects.PROJID = 1312184

在php Yii上运行相同的查询

$sql = "UPDATE `hdb`.`projects` 
   LEFT JOIN (
     SELECT 
       jobs.PROJID, round(SUM(jobs.value),2) AS SumOfJobValues,
       round(Sum(jobs.Earned),2) AS SumOfEarnedValues 
     FROM jobs  
     WHERE jobs.PROJID = :pid                                       
     GROUP BY jobs.PROJID
     as temp ON projects.PROJID = temp.PROJID                               
     SET
       projects.VALUE = round(SumOfJobValues,2), 
       projects.WIP = round(SumOfEarnedValues,2)
     WHERE projects.PROJID = :pid";

$command=$connection->createCommand($sql);
$command->bindValue(":pid",$model->PROJID,PDO::PARAM_INT);
$command->execute();

Answer 1

您忘记在Yii查询的第10行之前关闭括号。 此外，如果您不想加入NULL值，可以在JOIN定义中使用“IS NOT NULL”，例如：

UPDATE `hdb`.`projects` 
left JOIN (
  SELECT 
    jobs.PROJID, 
    round(SUM(jobs.value),2) AS SumOfJobValues,
    round(Sum(jobs.Earned),2) AS SumOfEarnedValues 
  FROM jobs         
  GROUP BY jobs.PROJID
) as temp ON (projects.PROJID = temp.PROJID) AND (temp.PROJID IS NOT NULL)
SET 
  projects.VALUE = round(SumOfJobValues,2), 
  projects.WIP = round(SumOfEarnedValues,2)
WHERE projects.PROJID = 1312184

编辑：我没有测试过这个。