SQL & PL/SQL

Hai All

I have a text line consist of 32 character and i have splitted this into four. And now now in the last emp code field i has four character so i need to add three before the string

for example
the text line is 00000000121212120102201016500123 and i have taken first 16 as barcode and 8 as date and 4 as time and now i need to replace or added 3 to the last string called empcode


M_barcode :=substr(mstr,1,16);
M_bardate := to_date(substr(mstr,17,8),'DD/MM/YYYY');
M_bartime := substr(mstr,25,4);

M_empcode:=substr()

Pls tell with example

Thanks & regards

Srikkanth.M