SQL：需要选择至少有 3 列不等于特定值的行

Question

我需要选择至少三列不等于“未知”的行

示例数据集：

id     condition_A      condition_B      condition_C     condition_D     Condition_E    
1      Unknown          Positive         Negative        Negative        Unknown
2      Unknown          Unknown          Negative        Negative        Unknown
3      Positive         Positive         Negative        Negative        Unknown

在这种情况下，我希望查询返回第 1 行和第 3 行。

Answer 1

我认为这会做到：

select * from tablename
where 3 <=
  (condition_A <> 'Unknown')::int + 
  (condition_B <> 'Unknown')::int + 
  (condition_C <> 'Unknown')::int + 
  (condition_D <> 'Unknown')::int + 
  (condition_E <> 'Unknown')::int

请参阅演示。
结果：

| id  | condition_a | condition_b | condition_c | condition_d | condition_e |
| --- | ----------- | ----------- | ----------- | ----------- | ----------- |
| 1   | Unknown     | Positive    | Negative    | Negative    | Unknown     |
| 3   | Positive    | Positive    | Negative    | Negative    | Unknown     |