mysql - 如何在我的 sql 表中获取数据时显示 0 而不是 NULL

Question

我正在从 mysql 表中获取数据，它工作正常，但它显示NULL在Status两个字段中。我想要而不是NULL表演0。

这是我的查询：

SELECT ml.GroupID, ml.GroupTitle, ml.GroupDescription, ml.GroupCreatedDateTime, ml.GroupOwnerUserID, ml.ApprovalNeeded, ml.GroupStatus, ml.OrganizationCode, cat.Status
FROM GroupsMaster AS ml
LEFT JOIN UserGroupsMapping cat ON cat.GroupID = ml.GroupID
WHERE ml.OrganizationCode = ?

Answer 1

使用COALESCE运算符

   COALESCE(cat.Status, 0)


SELECT 
 ml.GroupID, 
 ml.GroupTitle, 
 ml.GroupDescription, 
 ml.GroupCreatedDateTime, 
 ml.GroupOwnerUserID, 
 ml.ApprovalNeeded, 
 ml.GroupStatus, 
 ml.OrganizationCode, 
 COALESCE(cat.Status, 0) as Status 
FROM GroupsMaster AS ml 
LEFT JOIN UserGroupsMapping cat ON cat.GroupID = ml.GroupID 
WHERE ml.OrganizationCode = 'ibm' 

Answer 2

你可以试试ifnull()函数。如下所示：

选择ifnull (cat.status,0) 作为状态
FROM GroupsMaster AS ml LEFT JOIN UserGroupsMapping cat ON cat.GroupID = ml.GroupID WHERE ml.OrganizationCode = '$organizationCode'");

Answer 3

用这个

SELECT 
 ml.GroupID, 
 ml.GroupTitle, 
 ml.GroupDescription, 
 ml.GroupCreatedDateTime, 
 ml.GroupOwnerUserID, 
 ml.ApprovalNeeded, 
 ml.GroupStatus, 
 ml.OrganizationCode, 
 COALESCE(cat.Status, 0) as Status 
FROM GroupsMaster AS ml 
LEFT JOIN UserGroupsMapping cat ON cat.GroupID = ml.GroupID 
and ml.OrganizationCode = 'ibm'