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
时间： 2024-10-12 16:59:52