（1）用作日期轉換：

to_char(date,'格式');

select to_date('2005-01-01 ','yyyy-MM-dd') from dual; select to_char(sysdate,'yyyy-MM-dd HH24:mi:ss') from dual;

（2）處理數字：

to_char(number,'格式');

select to_char(88877) from dual;
select to_char(1234567890,'099999999999999') from dual; select to_char(12345678,'999,999,999,999') from dual; select to_char(123456
 
,'99.999') from dual; select to_char(1234567890,'999,999,999,999.9999') from dual;

（3）to_char(salary,'$99,99');

 select TO_CHAR(123,'$99,999.9') from dual;

（4）用於進位制轉換：將10進位制轉換為16進位制；

select to_char(4567,'xxxx') from dual; select to_char(123,'xxx') from dual;

例子：

 1 //// to_char 例子 
 
 
2 輸入    輸出
 3 to_char(now(),'Day, HH12:MI:SS')    'Tuesday , 05:39:18'
 4 to_char(now(),'FMDay, HH12:MI:SS')    'Tuesday, 05:39:18'
 5 to_char(-0.1,'99.99')    ' -.10'
 6 to_char(-0.1,'FM9.99')    '-.1'
 7 to_char(0.1,'0.9')    ' 0.1'
 8 to_char(12,'9990999.9')    ' 0012.0'
 9 to_char(12,'FM9990999.9')    '
 
0012'
10 to_char(485,'999')    ' 485'
11 to_char(-485,'999')    '-485'
12 to_char(485,'9 9 9')    ' 4 8 5'
13 to_char(1485,'9,999')    ' 1,485'
14 to_char(1485,'9G999')    ' 1 485'
15 to_char(148.5,'999.999')    ' 148.500'
16 to_char(148.5,'999D999')    ' 148,500'
17 to_char(3148.5,'9G999D999')    ' 3 148,500'
18 to_char(-485,'999S')    '485-'
19 to_char(-485,'999MI')    '485-'
20 to_char(485,'999MI')    '485'
21 to_char(485,'PL999')    '+485'
22 to_char(485,'SG999')    '+485'
23 to_char(-485,'SG999')    '-485'
24 to_char(-485,'9SG99')    '4-85'
25 to_char(-485,'999PR')    '<485>'
26 to_char(485,'L999')    'DM 485
27 to_char(485,'RN')    ' CDLXXXV'
28 to_char(485,'FMRN')    'CDLXXXV'
29 to_char(5.2,'FMRN')    V
30 to_char(482,'999th')    ' 482nd'
31 to_char(485, '"Good number:"999')    'Good number: 485'
32 to_char(485.8,'"Pre-decimal:"999" Post-decimal:" .999')    'Pre-decimal: 485 Post-decimal: .800'
33 to_char(12,'99V999')    ' 12000'
34 to_char(12.4,'99V999')    ' 12400'
35 to_char(12.45, '99V9')    ' 125'