invalid operands of types 'const char [21]' and 'const char*' to binary 'operato

Projects Networking, Protocols, and Devices
1

Dear Sir,

I am getting the error : "invalid operands of types 'const char [21]' and 'const char*' to binary 'operator+'"

on my code line : String sendData = "GET /update?api_key="+ myWriteAPIKey +"&"+ myFIELD +"="+String(sendVal);

In the code I have the following declarations:
const char * myWriteAPIKey ="77NQYR455QPFRN2G";

String myFIELD = "field1";
int sendVal;

Can you please tell me what is wrong in the code and how it can be corrected?

Thank you