Learn Mysql:mysql with Mr. Wang integer type of data type

Learn Mysql:mysql with Mr. Wang integer type of data type
Teacher: Wang Shaohua QQ Group No.: 483773664

MySQL data types include integer type, floating-point type, fixed-point number type, date and time type, string type, and binary data type.

Learning Goals

What types are included in an integral type and their range of values

Take tinyint as an example to explain the three attributes that define an integral type

First, Introduction

An integer type is the most basic data type in a database.

Both integer and smallint types are supported in standard SQL.

In addition to supporting these two types, the MySQL database extends support for tinyint, mediumint, and bigint.

Integer type is the most important to grasp its range of values

Ii. Range of values

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Third, take tinyint as an example (a) The design principles of the column

Storage: Range of storage

No waste: Occupy space

(ii) Creation of a table

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create tablestudent(   id int primary key auto_increment,   namevarchar(10),   age tinyint) charset utf8;

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(iii) Insert data 1 insert a normal value

1	insertintostudent(name,age)values(‘zhangsan‘,25);

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2 inserting a value greater than the range

1	insertintostudent(name,age)values(‘lisi‘,200);

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3 Inserting boundary values

1	insertintostudent(name,age)values(‘lisi‘,-128);

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(d) Optional attributes of integer type

1	数据类型 (显示宽度) unsigned zerofill

Display width: Only makes sense when filling at 0

Unsigned: Unsigned type (non-negative)

zerofill:0 Fill

1 unsigned

Add a column of unsigned type to student

1	altertable student addage2 tinyint unsigned;

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Add to Age2-1

insert into student ( name ,age,age2) values ( ' Lisi '

Learn Mysql:mysql with Mr. Wang integer type of data type

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