MySQL learning note--2. Column type

1.tinyint

Takes one byte and has a value range of -128~127

unsigned: unsigned, i.e. no negative (0~255)

Used in the representation of Boolean type/weight data

2.int //integral type

Accounted for four bytes

Zerofill: 0 padding without specifying unsigned

3.decimal (m,d) //floating-point

Compared to float, it is more precise

M,d: Total number of digits, number of decimal places

4.char (m) //fixed-length

The value range of M is 0~255

For data that is not long enough, the space is added automatically, although it is wasteful, but faster

5.varchar (m) //variable-length

The value range of M is 0~65535

6.text //text type

Its query speed is slow, try to use char or varchar instead

7.blob //binary type

For storing data such as images, audio, etc.

8.date //Date

Year-month-day range: 1000-01-01~9999-12-31

9.time //Time

Hours: minutes: seconds

10.datetime //Date Time

Year-month-day time: minutes: seconds

11.year //year

Range: 1901~2155 and 0000

12. Precautions

Try to use fixed length type, query efficiency is high; less use varchar, text length

Logon time does not use a datetime type and still uses the int type to store timestamps

@zhnoah
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MySQL learning note--2. Column type