Reference Url: Https://Www.Bilibili.Com/video/BV12b411K7Zu?P=132
1, numeric:
A , int
分类：tinyint(1)、smallint(2)、mediumint(3)、int/integer(4)、bigint(8)
a) The default is signed, to set an unsigned need to add unsigned keyword
b) to insert integer value exceeds the range, it will be reported out of range abnormality, and the insertion threshold
c) If you do not set the length, there will be a default length, the length represents the maximum width of the display, and if not will use 0 fill in on the left, but must be used with zerofill use
d) zero padding ZEROFILL , the default case for the unsigned integer
b , decimals:
classification:
a) fixed point
Dec(M,D)
Decimal(M,D)
b) Float
Float(M,D)
Double(M,D)
Features:
a)
M : integer portion of the fractional portion +
D : decimal site
If out of range, then the threshold value is inserted
b)
M and D can be omitted.
If a decimal, the M defaults to 10 , D defaults to 0
If float and Double , the value would be determined by the accuracy of the inserted
c) high accuracy fixed point, if asked to insert money value as high precision fixed-point arithmetic, consider using
d) principles:
Type chosen as simple as possible, to save the value type can be as small as possible
2 , character:
Short text: char , VARCHAR
Longer text: text , BLOB ( long binary data )
3, date:
1) Data only to save the date
2) Datatime save the date + time
3) Timestamp save the date + time
4) Time only save time
5) Year save only in