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返回字符的字符函数 1、CHR(n) [n为正整数,如果ngt;256,就去MOD(n,256)] select CHR(65) a1,CHR(67)||CHR(65)||CHR(84) a2 FR

返回字符的字符函数

1、CHR(n) [n为正整数,如果n>256,就去MOD(n,256)]

 

2、CONCAT(ch1,ch2) 拼接字符串[cha1,ch2为任意字符CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, NCLOB]

CONCAT(CLOB, NCLOB) returns NCLOB

CONCAT(NCLOB, NCHAR) returns NCLOB

CONCAT(NCLOB, CHAR) returns NCLOB

CONCAT(NCHAR, CLOB) returns NCLOB

 

3、INITCAP(ch) 单次首字母大写,其他小写

 

4、LOWER(ch) 将字符串转换为小写

 

5、LPAD(expr1,n,expr2) 从expr1中截取n个字符返回,如果长度不够就用expr2填充左边

 

6、LTRIM(ch,set)将字符串ch左边的包含在set中的字符移除,如股票不指定set,就为空格,中间有其他间隔就停止截取

 

7、NCHR(n) 相当于 CHR(n USINGNCHAR_CS)

 

8、NLS_INITCAP(ch,nlspara)针对字符串单词首字母大写,其余小写,可以指定排序规则nlspara,,也可以不指定采用默认规则

 

9、NLS_LOWER(ch, nlspara)将字符串转换为小写字母,可以指定排序规则

 

10、NLS_UPPER(ch, nlspara)将字符串转换为大写字母,可以指定排序规则

 

 

11、NLSSORT(ch, nlspara)返回字符串的字节码。用于排序



 

12、REGEXP_REPLACE(ch_source,pattern)正则表达式替换

 

13、REGEXP_SUBSTR(ch_source,pattern)正则表达式截取

 

14、REPLACE(ch,search_string,replace_string)字符串替换

 

15、RPAD(expr1,n,expr2) 从expr1中截取n个字符返回,如果长度不够就用expr2填充右边,默认填补空格

 

16、RTRIM(ch,set) 将字符串ch右边的包含在set中的字符移除,如股票不指定set,就为空格,中间有其他间隔就停止截取

 

17、SOUNDEX(ch) 返回字符串参数的语音表示形式,相对于比较一些读音相同,但是拼写不同的单词是非常有用的,在中文环境中没多大用处

 

18、SUBSTR(ch,position,length)截取字符串

 

19、TRANSLATE(ch,from_string,to_string)与REPLACE函数功能类似

针对ch字符串,将from_string中的字符串一一替换为to_string

 

20、TREAT

 

21、TRIM(ch fromsource_string) 去掉两边ch

TRIM(LEADINGch fromsource_string) 去掉左边ch

TRIM(TRAILINGch fromsource_string) 去掉右边ch

TRIM(BOTHch fromsource_string) 去掉两边 ch

 

22、UPPER(ch) 字符转换为大写

 

 

字符函数返回数值

1、ASCII(ch) 返回字符的ASCII码,ch可以是CHAR,VARCHAR2, NCHAR, or NVARCHAR2

 

2、INSTR(source,ch,position,n)在source中从位置position开始搜索ch,第n次出现的位置,没有匹配的返回0,默认从1开始第一次出现

 

3、LENGTH(ch) 返回字符串长度

 

4、REGEXP_COUNT(source_string,pattern,position,match_para)

正则表达式规则匹配字符串在原字符串中出现的次数

 

5、REGEXP_INSTR(source_string,pattern)正则表达式匹配字符串位置

 

NLS字符函数

1、NLS_CHARSET_DECL_LEN(byte_count,char_set_id)

返回一个 NCHAR 列的声明长度(也就是字符个数)。byte_count 参数是列的宽度。'char_set_id' 参数是字符集 ID

 

2、NLS_CHARSET_ID(string)返回字符集名称 对应的字符集ID

 

3、NLS_CHARSET_NAME(number)返回字符集 ID对应的字符集名称

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