我有3个表，对sql来说是新的，我正在尝试将2个表（用户和任务）合并到公司或一个新表中。我需要的可能是将companies表下的taskid和userid替换为users任务和表中的taskid和userid，但是我得到一个错误

SELECT COMPANY.UserID, COMPANY.TaskID, (FirstName+' '+LastName) AS FullName, TASKS.TaskSubject, USERS.UserID
FROM USERS, TASKS, COMPANY
INNER JOIN COMPANY.UserID = USERS.UserID
INNER JOIN COMPANY.TaskID = TASKS.TaskSubject

USERS:

UserID  FirstName   LastName 
1         John      Green 
2         Graham    Dale-Jones 
3         Francois  Peters 
4         Danika    Snow 
5         Jennifer  Booth 
6         Erin      Harvey 
7         Caleb     Jackson

TASKS:

TaskID TaskSubject     TaskManager
101      Install
102      Upgrade
103      Troubleshoot
104      Assign

COMPANY:

CompanyID TasksID UserID
1          101     1
1          101     2
2          102     2
3          103     3
4          103     4
5          104     7

谢谢你的帮助