Please help me in this scenario

i have two text files as below

file1.txt

Code:

record_1
conversion of a file;
code change;
data types;
lenght;
end;

record_2
field name;
string;
new fileline;
end;

record_3
address;
street;
zipcode;
state;
end;

file2.txt

Code:

record_2
field name;
string;
new fileline;
category;
decimal type;
end;

i want the output be like this in file1.txt

file1.txt

Code:

record_1
conversion of a file;
code change;
data types;
lenght;
end;

record_2
field name;
string;
new fileline;
category;
decimal type;
end;

record_3
address;
street;
zipcode;
state;
end;

i want to search for the record_2 pattern in file1 and using file2, if it exist i want to replace the whole line from record_2 to end; with the file2 content in file1. always my search pattern should replace lines between record_? through end; with second file.

please help me to solve this by using shell scripting.

Thanks in Advance,

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