c# - removing text from richtextbox -

i have richtextbox1 , want remove "user1". below , if sentence starts alter table , consists "user1". best way using c#

my text on richtextbox

drop index xie2tbl_a;  drop index xpktbl_a;  alter table "course" drop constraint "crse_crse_fk";  alter table "enrollment" drop constraint "enr_stu_fk";  alter table "enrollment" drop constraint "enr_sect_fk";  alter table "enrollment" add constraint "enr_stu_fk" foreign key ("student_id") references "user1"."student"("student_id") enable;  alter table "enrollment" add constraint "enr_sect_fk" foreign key ("section_id") references "user1"."section"("section_id") enable;  alter table "grade" drop constraint "gr_enr_fk";  alter table "grade" drop constraint "gr_grtw_fk";  alter table "grade" add constraint "gr_enr_fk" foreign key ("student_id","section_id") references "user1"."enrollment"("student_id","section_id") enable;  alter table "grade" add constraint "gr_grtw_fk" foreign key ("section_id","grade_type_code") references "user1"."grade_type_weight"("section_id","grade_type_code") enable;  alter table "grade_type_weight" drop constraint "grtw_grtyp_fk";  alter table "grade_type_weight" drop constraint "grtw_sect_fk";  alter table "grade_type_weight" add constraint "grtw_grtyp_fk" foreign key ("grade_type_code") references "user1"."grade_type"("grade_type_code") enable;  alter table "grade_type_weight" add constraint "grtw_sect_fk" foreign key ("section_id") references "user1"."section"("section_id") enable;  alter table "instructor" drop constraint "inst_zip_fk";  alter table "instructor" add constraint "inst_zip_fk" foreign key ("zip") references "user1"."zipcode"("zip") enable;  alter table "section" drop constraint "sect_inst_fk"; 

i want this:

  drop index xie2tbl_a;  drop index xpktbl_a;  alter table "course" drop constraint "crse_crse_fk";  alter table "enrollment" drop constraint "enr_stu_fk";  alter table "enrollment" drop constraint "enr_sect_fk";  alter table "enrollment" add constraint "enr_stu_fk" foreign key ("student_id") references "student"("student_id") enable;  alter table "enrollment" add constraint "enr_sect_fk" foreign key ("section_id") references "section"("section_id") enable;  alter table "grade" drop constraint "gr_enr_fk";  alter table "grade" drop constraint "gr_grtw_fk";  alter table "grade" add constraint "gr_enr_fk" foreign key ("student_id","section_id") references "enrollment"("student_id","section_id") enable;  alter table "grade" add constraint "gr_grtw_fk" foreign key ("section_id","grade_type_code") references "grade_type_weight"("section_id","grade_type_code") enable;  alter table "grade_type_weight" drop constraint "grtw_grtyp_fk";  alter table "grade_type_weight" drop constraint "grtw_sect_fk";  alter table "grade_type_weight" add constraint "grtw_grtyp_fk" foreign key ("grade_type_code") references "grade_type"("grade_type_code") enable;  alter table "grade_type_weight" add constraint "grtw_sect_fk" foreign key ("section_id") references "section"("section_id") enable;  alter table "instructor" drop constraint "inst_zip_fk";  alter table "instructor" add constraint "inst_zip_fk" foreign key ("zip") references "zipcode"("zip") enable;  alter table "section" drop constraint "sect_inst_fk"; 

for richtextbox1.text don't need check if each line starts alter table this:

 richtextbox1.text = richtextbox1.text.replace("references \"user1\".", "references "); 

if want check alter table, use little of regex:

regex reg = new regex("(alter table .+ references\\s+)\"user1\"[.](.+)"); richtextbox1.text = reg.replace(richtextbox1.text, "$1$2");