无法更新存储函数/触发器中的表'companystructures'，因为它已被调用此存储函数/触发器的语句使用

Question

I created a Before Insert trigger that generates a unique code for update on my table companystructures (in mysql). I keep getting when i try submitting my form.

Can't update table 'companystructures' in stored function/trigger because it is already used by statement which invoked this stored function/trigger

I'm quite new to this.

BEGIN
    DECLARE cd_count int;
    SET cd_count=0;
     IF NEW.type = 'Department' THEN
      INSERT INTO companystructures SET companystructures.comp_code = concat('D',(SELECT count(*) from companystructures WHERE type = 'Department')+1);

 ELSEIF NEW.type = 'Unit' THEN
  INSERT INTO companystructures SET companystructures.comp_code = concat('U', (SELECT count(*) from companystructures WHERE type = 'Unit')+1);

  ELSEIF NEW.type = 'Regional Office' THEN
  INSERT INTO companystructures SET companystructures.comp_code = concat('R', (SELECT count(*) from companystructures WHERE type = 'Regional Office')+1);

  ELSEIF NEW.type = 'Head Office' THEN
  INSERT INTO companystructures SET companystructures.comp_code = concat('H', (SELECT count(*) from companystructures WHERE type = 'Head Office')+1);

  ELSEIF NEW.type = 'Company' THEN 
  INSERT INTO companystructures SET companystructures.comp_code = concat('C', (SELECT count(*) from companystructures WHERE type = 'Company')+1);
 END IF;
 END