如何修改Count（*）结果

Question

需要修改计数结果。

输入查询：

SELECT COUNT(*) COLUMN_NAME 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = '<**TableName**>' 
 AND COLUMN_NAME IN ('**Column1Name**','**Column2Name**')

输出： 2

我的要求是，如果表中同时存在两列，则结果应为'1'。

有人可以通过简单的解决方案帮助我吗？

Answer 1

您可以进行聚合：

SELECT 1 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = '<**TableName**>' AND 
      COLUMN_NAME IN ('**Column1Name**','**Column2Name**')
GROUP BY TABLE_NAME
HAVING COUNT(*) = 2;

您必须确保HAVING COUNT(*) = 2的计数值与IN子句参数定义的计数值完全相同。

例如：

如果为COLUMN_NAME IN ('**Column1Name**','**Column2Name**', '**Column3Name**')，则HAVING子句为HAVING COUNT(*) = 3。

Answer 2

您缺少Have子句。

SELECT 1 COLUMN_NAME 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = '<**TableName**>' 
 AND COLUMN_NAME IN ('**Column1Name**','**Column2Name**') having count(*)=2

SELECT case when count(*)=2 then 1 else 0 end COLUMN_NAME 
    FROM INFORMATION_SCHEMA.COLUMNS 
    WHERE TABLE_NAME = '<**TableName**>' 
     AND COLUMN_NAME IN ('**Column1Name**','**Column2Name**') having count(*)=2

Answer 3

如果您想使用1或0，则可以使用case：

SELECT (CASE WHEN COUNT(*) = 2 THEN 1 ELSE 0 END)
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = '<**TableName**>' AND
      COLUMN_NAME IN ('**Column1Name**','**Column2Name**');