INSERT into direct table infotype Vs PA30 function

Hi Expert,

Could you adv what is significant differences between using INSERT sql command to insert data into PA infotype table compare with PA30 function (Using BDC)?

Could anyone give good example of using FM which have similar action with BDC PA30 function?

the reason is , i did create program to update infotype using INSERT Sql command but i have doubt that i miss several step behin PA30 function.

Please kindly help.

Thanks.

Rudy.