MySQL 检查空值或空值

Question

我需要帮助验证 mysql 中的空值或空值我尝试在我的案例中使用这种方式，但没有用：

SELECT
    CASE 
          WHEN account_type      IS NULL THEN 'Uninformed'
          WHEN account_type = ''         THEN 'Empty '
    END as Type,
COUNT(accounts.id)                     AS Total
FROM
accounts

有谁知道我该如何解决这个问题？

Answer 1

SELECT
CASE WHEN account_type IS NULL THEN 'Uninformed'
     WHEN account_type = ''  THEN 'Empty '
END as Type,
COUNT(accounts.id) AS Total
FROM accounts
group by account_type

您缺少 group by 子句。

Answer 2

您的查询是正确的。最后你需要添加 group by account_type;.

查询应该是这样的。

SELECT 
CASE WHEN account_type IS NULL THEN 'Uninformed'
        WHEN account_type = '' THEN 'Empty '
END AS Type,
COUNT(accounts.id) AS Total
FROM    accounts
GROUP BY account_type

Answer 3

另一种不使用 case 语句编写相同查询的巧妙方法类似于……

SELECT ISNULL(NULLIF(ISNULL(account_type , 'Uninformed'),''),'Empty') AS Type
     ,COUNT(accounts.id)                     AS Total
FROM accounts
GROUP BY ISNULL(NULLIF(ISNULL(account_type , 'Uninformed'),''),'Empty')

MySQL 检查空值或空值

MySQL check blank or null values

mysql

sql

null

case