这样的效果？你把表对应名称换成你的那个就成了..
CREATE TABLE TB1(LevelId INT,NAME VARCHAR(4))
INSERT INTO TB1(LevelId,NAME)
SELECT 1,'轻'
UNION ALL
SELECT 2,'中'
UNION ALL
SELECT 3,'重'

CREATE TABLE TB2(DangerId INT,UserId INT,LeveLId INT)
INSERT INTO TB2(DangerId,UserId,LeveLId)
SELECT 1,4,1
UNION ALL
SELECT 2,4,2
UNION ALL
SELECT 3,4,3
UNION ALL
SELECT 4,2,1
UNION ALL
SELECT 5,2,1
UNION ALL
SELECT 6,2,2
UNION ALL
SELECT 7,2,2
UNION ALL
SELECT 8,5,3
UNION ALL
SELECT 9,2,3
UNION ALL
SELECT 10,3,1

CREATE TABLE TB3(UserId INT,UserName VARCHAR(4))
INSERT INTO TB3(UserId,UserName) 
SELECT 2,'y'
UNION ALL
SELECT 3,'z'
UNION ALL
SELECT 4,'c'
SELECT 5,'q'
 --------
 SELECT * FROM TB1
 SELECT * FROM TB2
 SELECT * from TB3
----查询
;WITH
DD AS(
SELECT B.DangerId,A.UserName,B.LeveLId
FROM TB3 A LEFT JOIN 
     TB2 B
ON A.UserId=B.UserId
)
SELECT B.*,A.NAME
FROM TB1 A LEFT JOIN 
     DD B
ON A.LeveLId=B.LeveLId

-------
DangerId    UserName LeveLId     NAME
----------- -------- ----------- ----
1           c        1           轻
4           y        1           轻
5           y        1           轻
10          z        1           轻
2           c        2           中
6           y        2           中
7           y        2           中
3           c        3           重
9           y        3           重

(9 行受影响)

------解决方案--------------------
SQL code

少了个UNION ALL：
SELECT 4,'c'
SELECT 5,'q'
换成：
SELECT 4,'c'
UNION ALL
SELECT 5,'q'

q没插入进去
DangerId    UserName LeveLId     NAME
----------- -------- ----------- ----
1           c        1           轻
4           y        1           轻
5           y        1           轻
10          z        1           轻
2           c        2           中
6           y        2           中
7           y        2           中
3           c        3           重
8           q        3           重
9           y        3           重

(10 行受影响)

------解决方案--------------------
SQL code
SELECT
 isnull(LevelName,'') '程度',isnull(UserName,'') '姓名',isnull(COUNT(LevelName),'') as '次数'
FROM 
tb_Danger
LEFT JOIN
 tb_Level ON tb_Danger.LevelId = tb_Level.LevelId
FULL JOIN
 tb_Users ON tb_Danger.UserId = tb_Users.UserId --AND Limit = 1
GROUP BY
 LevelName,UserName order by LevelName desc