SQL

check constraint in sql

CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    City varchar(255),
    CONSTRAINT CHK_Person CHECK (Age>=18 AND City='Sandnes')
);

SQL CHECK Constraint

CREATE TABLE Orders (
  order_id INT PRIMARY KEY,
  amount INT CHECK (amount > 0)
);

check constraint in sql

#For one column
CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int CHECK (Age>=18)
);

check constraint in sql

#Add Check
ALTER TABLE Persons
ADD CONSTRAINT CHK_PersonAge CHECK (Age>=18 AND City='Sandnes');

#Drop Check 
ALTER TABLE Persons
DROP CHECK CHK_PersonAge;

SQL CHECK Constraint

CREATE TABLE Orders (
  order_id INT PRIMARY KEY,
  amount int CHECK (amount >= 100)
);

check constraint in ms sql

/*Adding Check constraint in sql server*/
ALTER TABLE (Table_Name)
ADD CONSTRAINT (Constraint_Name) CHECK (Boolean_Expression) 

SQL CHECK Constraint

CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    CHECK (Age>=18)
);