Dear Stata users,

In the following data, I want to replace variables d2a1 d2a2 d2a3 to missing 'cause variable d2a <100. Now I must type as many command lines as certain conditions.

Code:
replace d2a1=. if d2a==29
replace d2a1=. if d2a==8
replace d2a2=. if d2a==50
replace d2a3=. if d3a==50
......
Or:
Code:
replace d2a1=. if d2a<100
replace d2a2=. if d2a<100
replace d2a3=. if d3a<100
How to achieve that in a smarter way? (one command line and not so many "if", for example) Thank you.

Code:
    d2a1      d2a2      d2a3          d2a4        d2a
      29         0         0          2500         29
       8         0         0             0          8
       0        50         0         20000         50
      50         0         1          5000         50
       0         1         0         30000          1
       0        21         0         30000         21
      50         0         7          5000         57
      10        50         0         20000         60
      29         0         1          2500         30