Varchar2和char之间的主要区别是什么 [英] What is the major difference between Varchar2 and char

问题描述

创建表格：

CREATE TABLE test (
charcol    CHAR(10),
varcharcol VARCHAR2(10));

SELECT LENGTH(charcol), LENGTH(varcharcol) FROM test;

结果：

LENGTH(CHARCOL) LENGTH(VARCHARCOL)
--------------- ------------------
             10                  1 

请让我知道有什么区别Varchar2和char之间？

Please Let me know what is the difference between Varchar2 and char? At what times we use both?

推荐答案

显示区别的简单例子：

SELECT 
    '"'||CAST('abc' AS VARCHAR2(10))||'"', 
    '"'||CAST('abc' AS CHAR(10))||'"' 
FROM dual;


'"'||CAST('ABC'ASVARCHAR2(10))||'"' '"'||CAST('ABC'ASCHAR(10))||'"'
----------------------------------- -------------------------------
"abc"                               "abc       "                   
1 row selected.

CHAR是有用的表达式，其中charaters的长度总是解决，例如。美国各州的邮政编码，例如CA，NY，FL，TX

The CHAR is usefull for expressions where the length of charaters is always fix, e.g. postal code for US states, for example CA, NY, FL, TX

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