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 6¡¢show user; ÏÔʾµ±Ç°Á¬½ÓµÄÓû§   
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10¡¢select upper('coolszy') from dual; ½«Ð¡Ð´×Öĸת»»³É´óд£¬dual ÎªÒ»Ðé±í   
11¡¢select lower('KUKA') from dual; ½«´óд×Öĸת»»³ÉСд   
12¡¢select initcap('kuka') from dual; ½«Ê××Öĸ´óд    
13¡¢select concat('Hello',' world') from dual; Á¬½Ó×Ö·û´®£¬µ«Ã»ÓÐ||ºÃÓÃselect concat('Hello','world') from dual;   
14¡¢select substr('hello',1,3) from dual; ½ØÈ¡×Ö·û´®   
15¡¢select length('hello') from dual; Çó×Ö·û´®³¤¶È   
16¡¢select replace('hello','l','x') from dual; Ìæ»»×Ö·û´®    
17¡¢select substr('hello',-3,3) from dual; ½ØÈ¡ºóÈýλ   
  
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18¡¢select round(789.536) from dual; ËÄÉáÎåÈ룬ÉáȥСÊý   
19¡¢select round(789.536,2) from dual; ±£ÁôÁ½Î»Ð¡Êý   
20¡¢select round(789.536,-1) from dual; ¶ÔÕûÊý½øÐÐËÄÉáÎåÈë   
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