MySQL constraint conditions

This chapter describes: MySQL detailed operations on tables and constraints

To create a complete syntax for a table:

CREATE TABLE table name (field name Type, [(width) constraint]); #类型决定存储性质

The Char property is a string width of 1 is the storage limit #比如输入字符为 XY Only stores x can be adjusted to increase the character length

Constraint conditions :

Not NULL does not allow NULL to pass value

Field NULL displays whether the value of this field can be empty #int为整数类型 char is a string type

MySQL constraint conditions