Microsoft SQL Server DDL Commands: A Comprehensive Guide

In Microsoft SQL Server, Data Definition Language (DDL) commands are used to define and manage the structure of the database. DDL commands allow you to create, alter, and drop database objects such as tables, views, indexes, and stored procedures. In this article, we will explore the commonly used DDL commands in SQL Server and their syntax with examples.

CREATE

The CREATE statement is used to create new database objects. It allows you to create tables, views, indexes, functions, procedures, and more.

    CREATE TABLE table_name (
      column1 datatype,
      column2 datatype,
      ...
    );

    CREATE VIEW view_name AS
    SELECT column1, column2
    FROM table_name;
  

ALTER

The ALTER statement is used to modify the structure of existing database objects. You can use it to add or drop columns from a table, modify column data types, add constraints, and more.

    ALTER TABLE table_name
    ADD column_name datatype;

    ALTER TABLE table_name
    ALTER COLUMN column_name datatype;
  

DROP

The DROP statement is used to remove database objects from the database. It allows you to drop tables, views, indexes, functions, and more.

    DROP TABLE table_name;

    DROP VIEW view_name;
  

TRUNCATE

The TRUNCATE statement is used to remove all records from a table while keeping the table structure intact. It is faster than the DELETE statement as it does not log individual record deletions.

    TRUNCATE TABLE table_name;
  

RENAME

The RENAME statement is used to rename database objects such as tables and columns.

    EXEC sp_rename 'old_table_name', 'new_table_name';

    EXEC sp_rename 'table_name.old_column_name', 'new_column_name', 'COLUMN';
  

Conclusion

DDL commands play a crucial role in managing the structure of a database in Microsoft SQL Server. By understanding and utilizing the CREATE, ALTER, DROP, TRUNCATE, and RENAME statements, you can effectively create, modify, and remove database objects. These commands provide the flexibility and control needed to design and maintain a well-structured and efficient database.