student.id_civil_st like123456'
As you watch the error message closely you see you miss a space between your 'like' keyword and the value after that.
However as stated above in other suggestions, like is supposed to determine whether or not a given character string matches a pattern. The variables in this pattern are often noted by '%' as such:
Select * from student where student.id_civil_st like '%123456';
Otherwise if you want to compare a fixed number it's just fine to use the equality operator (=)