Oracle SQL函数之字符串函数
1.SQL> select ASCII('a'),ASCII('A'),CHR(97) from dual; --ASCLL（x）返回x的ASCLL码，CHR(x)返回ASCLL码为x的字符 ASCII('A') ASCII('A') CHR(97) ---------- ---------- ------- 97 65 a 2.SQL> SELECT NAME,INSTR(NAME,'Science') FROM PRODUCTS WHERE PRODUCT_ID=1; --显示字符串Science出现的位置 NAME INSTR(NAME,'SCIENCE') ------------------------------ --------------------- Modern Science 8 3.SQL> SELECT NAME,INSTR(NAME,'e',1,2) FROM PRODUCTS WHERE NAME LIKE'%e%e%'; --1表示从第1个字符开始，2表示出现次数2次 NAME INSTR(NAME,'E',1,2) ------------------------------ ------------------- Modern Science 11 2412: The Return 12 Space Force 9 11 From Another Planet 18 Creative Yell 8 4.SQL> SELECT CONCAT(FIRST_NAME || ' ', LAST_NAME) FROM CUSTOMERS; --concat(x,y)连接字符串xy CONCAT(FIRST_NAME||'',LAST_NAM ------------------------------ Cynthis Green JOHN BROWN Doreen Blue Steve White GAIL BLACK %test test 6 rows selected 5.SQL> SELECT INITCAP(DESCRIPTION) FROM PRODUCTS WHERE PRODUCT_ID<3; --inicat(x)，首字母大写 INITCAP(DESCRIPTION) -------------------------------------------------- A Description Of Modern Science Introduction To Chemistry 6.SQL> SELECT LENGTH(NAME) FROM PRODUCTS; --length(x），返回x的长度 LENGTH(NAME) ------------ 14 9 9 8 7 16 13 19 15 5 13 13 12 rows selected 7.SQL> SELECT NAME,LOWER(NAME),UPPER(NAME) FROM PRODUCTS; --转换为大小写 NAME LOWER(NAME) UPPER(NAME) ------------------------------ ------------------------------ ------------------------------ Modern Science modern science MODERN SCIENCE Chemistry chemistry CHEMISTRY Supernova supernova SUPERNOVA Tank War tank war TANK WAR Z Files z files Z FILES 2412: The Return 2412: the return 2412: THE RETURN Space Force 9 space force 9 SPACE FORCE 9 From Another Planet from another planet FROM ANOTHER PLANET Classical Music classical music CLASSICAL MUSIC Pop 3 pop 3 POP 3 Creative Yell creative yell CREATIVE YELL My Front Line my front line MY FRONT LINE 12 rows selected 8.SQL> SELECT RPAD(NAME,20,'-'),LPAD(PRICE,10,'*') FROM PRODUCTS; --RPAD(x，width,string)右填充，RPAD(x,width,string)左填充 RPAD(NAME,20,'-') LPAD(PRICE,10,'*') ---------------------------------------- -------------------- Modern Science------ *****19.95 Chemistry----------- ********30 Supernova----------- *****25.99 Tank War------------ *****13.95 Z Files------------- *****49.99 2412: The Return---- *****14.95 Space Force 9------- *****13.49 From Another Planet- *****12.99 Classical Music----- *****10.99 Pop 3--------------- *****15.99 Creative Yell------- *****14.99 My Front Line------- *****13.49 12 rows selected 9.SQL> SELECT LTRIM(' HELLO RUSKY'),RTRIM('HELLO RUSKY ABCDE','EDCB'),TRIM('AB' FROM 'ABC HELLO RUSKY ABCDEA') FROM DUAL; SELECT LTRIM(' HELLO RUSKY'),RTRIM('HELLO RUSKY ABCDE','EDCB'),TRIM('AB' FROM 'ABC HELLO RUSKY ABCDEA') FROM DUAL ORA-30001: 截取集仅能有一个字符 SQL> SELECT LTRIM(' HELLO RUSKY'),RTRIM('HELLO RUSKY ABCDE','EDCB'),TRIM('A' FROM 'ABC HELLO RUSKY ABCDEA') FROM DUAL; LTRIM('HELLORUSKY') RTRIM('HELLORUSKYABCDE','EDCB' TRIM('A'FROM'ABCHELLORUSKYABCD ------------------- ------------------------------ ------------------------------ HELLO RUSKY HELLO RUSKY A BC HELLO RUSKY ABCDE
SQL> select ltrim('abcdefg','abc')from dual;
LTRIM('ABCDEFG','ABC')
----------------------
defg
说明：LTRIM(x,string)从X左边开始截去string中的字符串 RTRIM(x,string)从X右边开始截去string中的字符串 TRIM(string FROM x)从x的左右两边截去string 这三个函数，如果不指定string，则默认截去x中的空格。
10.SQL> SELECT CUSTOMER_ID,NVL(PHONE,'Unknown Phone Number') FROM CUSTOMERS; --NVL(x,value),如果x为空，则返回values CUSTOMER_ID NVL(PHONE,'UNKNOWNPHONENUMBER' --------------------------------------- ------------------------------ 2 800-555-1212 1 11223344 5 Unknown Phone Number 3 800-555-1213 4 1234 6 Unknown Phone Number 6 rows selected 11.SQL> SELECT CUSTOMER_ID,NVL2(PHONE,'Known','Unknown') FROM CUSTOMERS; --NVL2(x,value1,value2)如果x非空，返回value1,如果x为空，返回value2 CUSTOMER_ID NVL2(PHONE,'KNOWN','UNKNOWN') --------------------------------------- ----------------------------- 2 Known 1 Known 5 Unknown 3 Known 4 Known 6 Unknown 6 rows selected 12.SQL> SELECT NAME,REPLACE(NAME,'Science','Physics') FROM PRODUCTS WHERE PRODUCT_ID=1; --REPLACE(x,search_string,replace_string),在x中查找search_string,并替换为replace_string NAME REPLACE(NAME,'SCIENCE','PHYSIC ------------------------------ -------------------------------------------------------------------------------- Modern Science Modern Physics 13.SQL> SELECT LAST_NAME FROM CUSTOMERS WHERE SOUNDEX(LAST_NAME)=SOUNDEX('WHYTE'); --SOUNDEX(x)查找发音相似的单词 LAST_NAME ---------- White 14.SQL> SELECT NAME,SUBSTR(NAME,2,7) FROM PRODUCTS; --SUBSTR(x,start,length)从x中的start位置，截取指定长度length的字符 NAME SUBSTR(NAME,2,7) ------------------------------ ---------------- Modern Science odern S Chemistry hemistr Supernova upernov Tank War ank War Z Files Files 2412: The Return 412: Th Space Force 9 pace Fo From Another Planet rom Ano Classical Music lassica Pop 3 op 3 Creative Yell reative My Front Line y Front 12 rows selected 15.SQL> SELECT NAME,SUBSTR(NAME,2) FROM PRODUCTS; --如果不指定length，则从第2个字符截取后面全部 NAME SUBSTR(NAME,2) ------------------------------ ---------------------------------------------------------- Modern Science odern Science Chemistry hemistry Supernova upernova Tank War ank War Z Files Files 2412: The Return 412: The Return Space Force 9 pace Force 9 From Another Planet rom Another Planet Classical Music lassical Music Pop 3 op 3 Creative Yell reative Yell My Front Line y Front Line 12 rows selected 15.SQL> SELECT NAME,UPPER(SUBSTR(NAME,2,8)) FROM PRODUCTS; --使用组合函数 NAME UPPER(SUBSTR(NAME,2,8)) ------------------------------ ----------------------- Modern Science ODERN SC Chemistry HEMISTRY Supernova UPERNOVA Tank War ANK WAR Z Files FILES 2412: The Return 412: THE Space Force 9 PACE FOR From Another Planet ROM ANOT Classical Music LASSICAL Pop 3 OP 3 Creative Yell REATIVE My Front Line Y FRONT 12 rows selected