一、Lpad函数

lpad函数将左边的字符串填充一些特定的字符其语法格式如下：lpad(string,n,[pad_string])

string:字符或者参数

n:字符的长度，是返回的字符串的数量，如果这个数量比原字符串的长度要短，lpad函数将会把字符串截取成从左到右的n个字符;

pad_string:可选参数，这个字符串是要粘贴到string的左边，若这个参数未写，lpad函数将会在string的左边粘贴空格。

select lpad('tech', 7) from dual; 将返回' tech'
select lpad('tech', 2) from dual; 将返回'te'
select lpad('tech', 8, '0') from dual; 将返回'0000tech'
select lpad('tech on the net', 15, 'z') from dual; 将返回'tech on the net'
select lpad('tech on the net', 16, 'z') from dual; 将返回'ztech on the net'

SQL> select lpad('tech', 7) from dual;

LPAD('T
-------
tech

SQL> select lpad('tech', 2) from dual;

LP
--
te

SQL> select lpad('tech', 8, '0') from dual;

LPAD('TE
--------
0000tech

SQL> select lpad('tech on the net', 15, 'z') from dual;

LPAD('TECHONTHE
---------------
tech on the net

SQL> select lpad('tech on the net', 16, 'z') from dual;

LPAD('TECHONTHEN
----------------
ztech on the net

SQL>

二、Rpad函数

rpad函数将右边的字符串填充一些特定的字符其语法格式如下：rpad(string,n,[pad_string])

string：字符或者参数

n：字符的长度，是返回的字符串的数量，如果这个数量比原字符串的长度要短，lpad函数将会把字符串截取成从左到右的n个字符;

pad_string：可选参数，这个字符串是要粘贴到string的右边，如果这个参数未写，lpad函数将会在string的右边粘贴空格。

select rpad('tech', 7) from dual; 将返回' tech'
select rpad('tech', 2) from dual; 将返回'te'
select rpad('tech', 8, '0') from dual; 将返回'tech0000'
select rpad('tech on the net', 15, 'z') from dual; 将返回'tech on the net'
select rpad('tech on the net', 16, 'z') from dual; 将返回'tech on the netz'

SQL> select rpad('tech', 7) from dual;

RPAD('T
-------
tech

SQL> select rpad('tech', 2) from dual;

RP
--
te

SQL> select rpad('tech', 8, '0') from dual;

RPAD('TE
--------
tech0000

SQL> select rpad('tech on the net', 15, 'z') from dual;

RPAD('TECHONTHE
---------------
tech on the net

SQL> select rpad('tech on the net', 16, 'z') from dual;

RPAD('TECHONTHEN
----------------
tech on the netz

ITPub博客

lpad/rpad函数

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