how to split a column value into multiple rows in flink sql?

[1095193...@qq.com]

Hi
  For example , a table like this:
   A     B      C
  ------------------
   a1   b1    c1,c2,c3
  -------------------
  how to split c1,c2,c3 into multiple rows like this in flink sql function:
A  B   C
--------
a1  b1  c1
a1  b1  c2
a1  b1  c3 Thank you



1095193...@qq.com