DEFAULT

Constraint

Specifies a default value for a column when no value is provided during INSERT.

Syntax

col type DEFAULT value

Example

CREATE TABLE posts (
  id SERIAL PRIMARY KEY,
  status VARCHAR(20) DEFAULT 'draft',
  created_at TIMESTAMP DEFAULT NOW()
);

About SQL DEFAULT

The DEFAULT keyword belongs to the Constraint category of SQL statements. Specifies a default value for a column when no value is provided during INSERT. Understanding this command is essential for any developer working with relational databases like PostgreSQL, MySQL, SQLite, or SQL Server.

SQL (Structured Query Language) is the standard language for managing and querying relational databases. The DEFAULT statement is supported across all major database systems, though specific syntax may vary slightly between PostgreSQL, MySQL, MariaDB, Oracle, SQL Server, and SQLite. Always consult your database's documentation for vendor-specific features and limitations.

Best practices for using DEFAULT: always test queries on a development database before running them in production, use parameterized queries to prevent SQL injection, and leverage EXPLAIN to understand query performance. For complex queries, consider using CTEs (Common Table Expressions) to improve readability and maintainability.

Related SQL Keywords

NOT NULL INSERT INTO ALTER TABLE CREATE TABLE