合并两个配置单元表（不同列大小）-pyspark

我有一个带有模式的配置单元表 姓名、联系人、地址、主题

Name  Contact   Address  Subject
abc   1111      Mumbai    maths
egf   2222      nashik    science
pqr   3333      delhi     history

And other table with schema **Name ,Contact** 
Name   Contact
xyz    4444  
mno    2222 

预期产量

Name  Contact   Address  Subject
abc   1111      Mumbai    maths
pqr   3333      delhi     history
xyz   4444      null      null
mno   2222      nashik    science

我已尝试联接操作，但无法获得正确的输出

使用完全联接：

select coalesce(t2.name,t1.name) as name, 
       coalesce(t2.contact, t1.contact) as contact,
       t1.address, t1.subject
  from table1 t1
       full join table2 t2
                 on t1.contact=t2.contact

使用完全联接：

select coalesce(t2.name,t1.name) as name, 
       coalesce(t2.contact, t1.contact) as contact,
       t1.address, t1.subject
  from table1 t1
       full join table2 t2
                 on t1.contact=t2.contact