Extract values from lookup tables and display

[guoxin]

Hi All,

I've encountered a problem which i find for answers but to no avail and i hope you all can help. I've got 4 tables namely, User_Login, Admin_Login, Projects and Mapping.

User_Login
-user_id (PK) INTEGER NOT NULL AUTO INCREMENT
-user_username VARCHAR(30) NOT NULL
-user_password VARCHAR(30) NOT NULL

Admin_Login
-admin_username VARCHAR(30) NOT NULL
-admin_password VARCHAR(30) NOT NULL

Projects
-project_id (PK) INTEGER NOT NULL AUTO INCREMENT
-project_name VARCHAR(30) NOT NULL

Mapping
-user_id (FK)
-project_id (FK)

Mapping is used as a lookup table when the administrator want to assign projects to the newly created user so we use the user_id from User_Login and project_id form Projects as a reference.

But here comes the problem, i execute the following command, $sql = "SELECT project_name FROM Projects, Mapping, User_Login WHERE Mapping.user_id=User_Login.user_id AND Mapping.project_id=Projects.project_id"; so the scenario is when a particular user is logged in, the projects will be displayed in a dropdown list where user can select which project he/she want to submit. But the dropdown list won't show up anything so i'm really asking you all for help. I'll be really grateful Thanks.

[amitpatel66]

Hi All,

I've encountered a problem which i find for answers but to no avail and i hope you all can help. I've got 4 tables namely, User_Login, Admin_Login, Projects and Mapping.

User_Login
-user_id (PK) INTEGER NOT NULL AUTO INCREMENT
-user_username VARCHAR(30) NOT NULL
-user_password VARCHAR(30) NOT NULL

Admin_Login
-admin_username VARCHAR(30) NOT NULL
-admin_password VARCHAR(30) NOT NULL

Projects
-project_id (PK) INTEGER NOT NULL AUTO INCREMENT
-project_name VARCHAR(30) NOT NULL

Mapping
-user_id (FK)
-project_id (FK)

Mapping is used as a lookup table when the administrator want to assign projects to the newly created user so we use the user_id from User_Login and project_id form Projects as a reference.

But here comes the problem, i execute the following command, $sql = "SELECT project_name FROM Projects, Mapping, User_Login WHERE Mapping.user_id=User_Login.user_id AND Mapping.project_id=Projects.project_id"; so the scenario is when a particular user is logged in, the projects will be displayed in a dropdown list where user can select which project he/she want to submit. But the dropdown list won't show up anything so i'm really asking you all for help. I'll be really grateful Thanks.

Firstly, please check if any projects are assigned to any used who is logging in?