CREATEORREPLACEPROCEDUREadd_employee( emp_idINT, emp_nameVARCHAR, emp_salaryNUMERIC, emp_departmentVARCHAR )LANGUAGEplpgsqlAS$$ BEGIN INSERTINTOemployees (id, name, salary, department) VALUES (emp_id, emp_name, emp_salary, emp_department); END; $$; 创建存储过程报错： ERROR: syntax error at or near "LANGUAGE"