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SQL验证字符串是否包含有大小写字母
分类:数据库

What does "size" in int(size) of MySQL mean?

SHOW PROCESSLIST

or

 show status where `variable_name` = 'Threads_connected';

昨晚有实现一个小功能,就是在MS SQL Server中,检查字符串是否包含有大小写字母。通常应用在字符串的复杂度。

图片 1

 

图片 2图片 3

Friday, August 24th, 2007 at 21:40 +0000 (UTC) by Alexander Kirk

DECLARE @s NVARCHAR(40) = N'SDFfgGRYJhhTYUJ'


IF LOWER(@s) COLLATE Latin1_General_CS_AS <> @s AND UPPER(@s) COLLATE Latin1_General_CS_AS <> @s
    PRINT 'T'
ELSE
    PRINT 'F'

I was always wondering what the size of numeric columns in MySQL was. Forgive me if this is obvious to someone else. But for me the MySQL manual lacks a great deal in this field.

Source Code

TL;DR: It's about the display width. You only see it when you use ZEROFILL.

实时操作演示,空符串,全部小写,全部大写,大小混写等状况:
图片 4

Usually you see something like int(11) in CREATE TABLE statements, but you can also change it to int(4).

 

So what does this size mean? Can you store higher values in a int(11) than in an int(4)?

Let's see what the MySQL manual says:

INT[(M)] [UNSIGNED] [ZEROFILL]
A normal-size integer. The signed range is -2147483648 to 2147483647. The unsigned range is 0 to 4294967295.

No word about the M. The entry about BOOL suggests that the size is not there for fun as it is a synonym forTINYINT(1) (with the specific size of 1).

TINYINT[(M)] [UNSIGNED] [ZEROFILL]
A very small integer. The signed range is -128 to 127. The unsigned range is 0 to 255.

BOOL, BOOLEAN
These types are synonyms for TINYINT(1). A value of zero is considered false. Non-zero values are considered true: […]

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