How to execute the batch apex class using developer console?
Example:
Batch Apex Class:

global class accountList implements Database.Batchable<Sobject> {
global Database.querylocator start(Database.BatchableContext BC) {
return Database.getQueryLocator([select Id, Name from Account]);
}
global void execute(Database.BatchableContext BC, list<Account> scope) {
return Database.getQueryLocator(query);
}
global void finish(Database.BatchableContext BC) {
}
}

Execute the Batch Apex Class using Developer Console using below,

accountList objTest = new accountList();
Database.executebatch(objTest);

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