SQL PRIMARY KEY Constraint - W3Schools
SQL PRIMARY KEY Constraint. The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table …
MySQL PRIMARY KEY Constraint - W3Schools
The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary …
SQL FOREIGN KEY Constraint - W3Schools
SQL FOREIGN KEY Constraint. The FOREIGN KEY constraint is used to prevent actions that would destroy links between tables. A FOREIGN KEY is a field (or collection of fields) in one …
MySQL FOREIGN KEY Constraint - W3Schools
MySQL FOREIGN KEY Constraint. The FOREIGN KEY constraint is used to prevent actions that would destroy links between tables. A FOREIGN KEY is a field (or collection of fields) in one …
Python MySQL Create Table - W3Schools
Primary Key. When creating a table, you should also create a column with a unique key for each record. This can be done by defining a PRIMARY KEY. We use the statement "INT …
PostgreSQL Create Table - W3Schools
To create a new database table using the SQL Shell, make sure you are connected to the database. If not, follow the steps in the Get Started chapter of this tutorial. Once you are …
SQL Tryit Editor v1.6 - W3Schools
SQL Statement: CREATE TABLE Persons ( PersonID int, LastName varchar(255), FirstName varchar(255), Address varchar(255), City varchar(255) ); Edit the SQL Statement, and click …
MySQL CREATE TABLE Statement - W3Schools
The MySQL CREATE TABLE Statement. The CREATE TABLE statement is used to create a new table in a database. Syntax
PHP MySQL Create Table - W3Schools
PRIMARY KEY - Used to uniquely identify the rows in a table. The column with PRIMARY KEY setting is often an ID number, and is often used with AUTO_INCREMENT; Each table should …
Node.js MySQL Create Table - W3Schools
Primary Key. When creating a table, you should also create a column with a unique key for each record. This can be done by defining a column as "INT AUTO_INCREMENT PRIMARY KEY" …