Creating Tables in SQL Server - Examples Tutorial

Basic CREATE TABLE Syntax

The CREATE TABLE statement defines a new table and its columns in SQL Server.

Each column requires a name and a data type. Additional constraints can be added to enforce rules.

• Syntax: CREATE TABLE table_name (column1 datatype [constraints], column2 datatype [constraints], ...);
• Data types specify the kind of data stored, such as INT, VARCHAR, DATE, etc.
• Constraints include PRIMARY KEY, NOT NULL, UNIQUE, DEFAULT, and FOREIGN KEY.

Creating a Simple Table Example

Let's create a simple table named Employees with basic columns.

Adding Constraints to Tables

Constraints help maintain data integrity by enforcing rules on the data entered into tables.

Common constraints include PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL, and DEFAULT.

• PRIMARY KEY uniquely identifies each row.
• FOREIGN KEY enforces referential integrity between tables.
• NOT NULL ensures a column cannot have NULL values.
• DEFAULT assigns a default value if none is provided.

Using Default Values and Nullability

You can specify default values for columns and control whether columns accept NULLs.

This helps ensure consistent data entry and reduces errors.

• DEFAULT sets a value automatically if none is provided during insert.
• NOT NULL forces a value to be provided; NULL allows missing data.