Writing Something

SELECT  upper(substr(FIRST_NAME,0,1)) ||'. '|| initcap(LAST_NAME) AS "Özel Ad",
        concat(FIRST_NAME,LAST_NAME), 
        length(LAST_NAME),
        lower(LAST_NAME),        
        instr(LAST_NAME,'s'),
        lpad(SALARY, 6,'0'),
        rpad(EMAIL, 10,'-'),
        REPLACE(LAST_NAME,'i',' I '),
        trim('K' FROM LAST_NAME)
FROM EMPLOYEES
WHERE upper(last_name) = Upper('KiNg')
  OR substr(JOB_ID,4)='PROG';
 
SELECT substr('SERDAR',1,3)
FROM DUAL;
 
SELECT round(45.926,2), round(45.926,-1), round(155.926,-2), 
           round(43.926,-1), round(45.926)
FROM DUAL;
 
SELECT trunc(45.926, 2), trunc(45.926), trunc(45.926,-1)
FROM DUAL;
 
SELECT SALARY, mod(salary,1000), round(salary*1.18)
FROM EMPLOYEES;
 
SELECT sysdate+7,sysdate
FROM DUAL;
 
SELECT HIRE_DATE,round(sysdate-HIRE_DATE) AS GUNSAYISI,
                  round((sysdate-HIRE_DATE)/7) AS HAFTA
FROM EMPLOYEES
ORDER BY GUNSAYISI;
 
SELECT months_between(sysdate, HIRE_DATE), 
        add_months(HIRE_DATE,5),
        next_day(HIRE_DATE,'monday'),
        last_day(sysdate)    
FROM EMPLOYEES;
 
 
SELECT round(sysdate,'month'),
       round(sysdate,'year'),
        trunc(sysdate,'month'),
        trunc(sysdate,'year') 
FROM DUAL;
 
 
ALTER session SET nls_date_format ='DD-MM-YYYY HH24:MI:SS';
ALTER system SET nls_date_format ='DD-MM-YYYY HH24:MI:SS';
 
SELECT to_char(sysdate,'FMDAY - MONTH - YEAR'),to_char(sysdate,'DAY-MONTH-YEAR')
FROM dual;
 
SELECT to_char(salary,'$99,999.99')
FROM employees;
 
SELECT sysdate,lower(to_char(sysdate,'fmddspth - month - year')) 
FROM dual;
 
SELECT last_name, to_char(hire_date,'dd - Mon - yyyy')
FROM employees
WHERE hire_date < to_date('01-Jan-90','dd-mon-rr');
 
SELECT nvl(to_char(commission_pct),'Komisyon Almıyor'), 
        nvl2(commission_pct,'Komisyon Alıyor','Komisyon Almıyor'),
        nullif(length(last_name),length(first_name)) AS dif,
        coalesce(to_char(commission_pct),to_char(manager_id),'bişey yok')        
FROM employees;
 
SELECT last_name, job_id,
  case job_id when 'IT_PROG' then 1.10*salary
              when 'ST_CLERK' then 1.15*salary
  else salary
  end "CASEDEN DONEN SALARY", department_id
FROM employees;
 
SELECT last_name, job_id,
  decode(job_id,'IT_PROG',1.10*salary,
                'ST_CLERK',1.15*salary,
  salary)
  REVISED_SALARY
FROM employees;