SQL PRIMARY KEY Constraint - W3Schools
SQL PRIMARY KEY Constraint The PRIMARY KEY constraint is used to uniquely identify each record in a table. Primary keys must contain unique values, and cannot contain NULL values. Each table …
MySQL PRIMARY KEY Constraint - W3Schools
MySQL 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 can …
SQL FOREIGN KEY Constraint - W3Schools
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 table, that refers to the PRIMARY KEY in …
W3Schools SQL Exercise
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PHP MySQL Create Table - W3Schools
The CREATE TABLE statement is used to create a table in MySQL. We will create a table named "MyGuests", with five columns: "id", "firstname", "lastname", "email" and "reg_date":
Node.js MySQL Create Table - W3Schools
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" which will insert a unique …
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 AUTO_INCREMENT …
MySQL CREATE TABLE Statement - W3Schools
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MySQL UNIQUE Constraint - W3Schools
Both the UNIQUE and PRIMARY KEY constraints provide a guarantee for uniqueness for a column or set of columns. A PRIMARY KEY constraint automatically has a UNIQUE constraint.
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.