mysql NOT NULL constraint
Translation results：
not
UK[nɒt] US[nɑ:t]
adv.No; [used to express negation, denial, rejection, prohibition, etc.] No ; Hardly; Not necessarily, no [used to negate the following word or phrase]
null
UK[nʌl] 美[nʌl]
adj.<Art>zero value; equal to zero; (agreement) has no legal effect; invalid
mysql NOT NULL constraintsyntax
Function: Constraint forces the column not to accept NULL values.
Description: NOT NULL constraint forces the field to always contain a value. This means that you cannot insert a new record or update a record without adding a value to the field.
mysql NOT NULL constraintexample
//强制 "Id_P" 列和 "LastName" 列不接受 NULL 值 CREATE TABLE Persons(Id_P int NOT NULL,LastName varchar(255) NOT NULL,FirstName varchar(255),Address varchar(255),City varchar(255));
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