mysql - mysql中的SELECT中的IF语句

如果workspace.assigned_to = NULL ELSE不选择任何内容，如何选择列。

SELECT workspace.*, projects.*,
  CASE
    WHEN workspace.assigned_to != NULL
    THEN users.user_id,users.first_name, users.last_name
   END FROM workspace
INNER JOIN projects ON workspace.workspace_id = projects.project_id
INNER JOIN users ON workspace.assigned_to = users.user_id
WHERE project_id=:project_id

最佳答案

SELECT workspace.*, projects.*,
  users.user_id,users.first_name, users.last_name
FROM workspace
INNER JOIN projects ON workspace.workspace_id = projects.project_id
LEFT JOIN users ON workspace.assigned_to = users.user_id
WHERE project_id=:project_id

LEFT JOIN表示我们通过Assigned_to加入用户，但如果为null，则用户的valuea为null

关于mysql - mysql中的SELECT中的IF语句，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/34378991/