user select via IWorkspace.ExecuteSQL on filegdb(*.gdb)

[zszs]

on filegdb(*.gdb),i am executing sql via IWorkspace.ExecuteSQL method,but some sql can not execute: insert into tba(...) select ... from tbb,my purpose is copy tba's all values to tbb,how to solve it use IWorkspace.ExecuteSQL
thanks

[zszs]

and alter column sql will thrown exception:alter table tb alter column Clm float
is filegbd(*.gdb) support this sql?