右连接查询不起作用 - 4个表

Question

我的查询和它的＆＃39;可以只有两个表：

SELECT
CASE WHEN p.name IS NULL THEN i.number2 ELSE p.name END as Names
FROM tbl1 p
RIGHT JOIN tbl2 i ON p.number = i.number2
GROUP BY i.number2 

我有四张桌子：

tbl1
number name
+72001 Patrick
+72002 Ivan

tbl2
number2 text2
+72001  ABC1
+72003  ABC2

tbl3
number3 text3
+72002  ABC5
+72004  ABC6

tbl4
number4 text4
+72001  ABC5
+72005  ABC6

如果我想要使用4个表并且结果如下：

number
Patrick
Ivan
+72003
+72004
+72005

我尝试之后，现在正在运行：

SELECT
    CASE WHEN p.name IS NULL THEN i.number2 ELSE p.name END AS  NAMES 
FROM tbl1 p
RIGHT JOIN tbl2 i ON p.number = i.number2
GROUP BY NAMES

UNION 

SELECT CASE WHEN p.name IS NULL THEN m.number3 ELSE p.name END AS NAMES 
FROM tbl1 p
RIGHT JOIN tbl3 m ON p.number = m.number3
GROUP BY NAMES 

UNION 

SELECT CASE WHEN p.name IS NULL THEN n.number4 ELSE p.name END AS NAMES 
FROM tbl1 p
RIGHT JOIN tbl4 n ON p.number = n.number4
GROUP BY NAMES