Question

是否有人知道是否可以在一个查询中执行以下操作而不是执行数字？

$select1 = "SELECT service FROM UPSServices WHERE code = '$serviceCode' AND ship_from_code = '$shipFrom'";

$result = mssql_query($select1);

//print_r($result);

if(mssql_num_rows($result) == 0) {
    $select2 = "SELECT service FROM UPSServices WHERE code = '$serviceCode' AND ship_from_code IS NULL";
    $result = mssql_query($select2);
}

while ($service = mssql_fetch_array($result)) {
    return $service['0'];
}

Answer 1

您正在使用SQL Server，因此您可以执行此操作。它比你想象的要复杂一些。以下版本计算有效值的数量。如果它大于0，则过滤掉NULL。

select service    
from (SELECT service,
             count(ship_from_code) over () as NumValues
      FROM UPSServices
      WHERE code = '$serviceCode' AND (ship_from_code = '$shipFrom' OR ship_from_code IS NULL) 
    ) t
where (NumValues > 0 and service is not NULL) or (NumValues = 0 and service is NULL)
limit 1

Answer 2

如果指定的shipCode不存在，我认为你需要使用NULL shipCode的值

SELECT service FROM UPSServices WHERE 
code = '$serviceCode' AND (ship_from_code = '$shipFrom' OR ship_from_code IS NULL) 
ORDER BY ship_from_code"

如果您的船舶代码存在，那么请按顺序确保其位于顶部

SQL Server查询 - 组合查询

2 个答案: