我想找出同一个数据表中两个变量同一iD之间相同的项，请问该如何做？
下面是例子：我想找出id为16的两个变量之间的共同值A和H;ID为20的两个变量的共同值M;ID为25的两个两个变量没有共同项。var1和var2实际上是股东名称，我想匹配共同股东。




附：

clear
input str3(id var1 var2)
"16" "A" "C"
"16" "B" "F"
"16" "H" "A"
"16" "D" "L"
"16" "N" "H"
"20" "M" "M"
"20" "F" "S"
"20" "D" "Q"
"20" "I" "L"
"25" "Q" "A"
"25" "M" "C"
"25" "F" "S"
"25" "D" "P"
"25" "I" "L"
end