What is SQL DML and how does it ensure data integrity?

What is SQL DML and how does it ensure data integrity?

SQL DML, or Data Manipulation Language, is used to manage data within relational databases. It includes commands like INSERT, UPDATE, and DELETE. Data integrity is ensured through constraints like primary keys, foreign keys, and unique constraints that maintain accuracy and consistency.

Can you explain how primary keys contribute to data integrity?

Primary keys uniquely identify each record in a table, preventing duplicate entries. This ensures that each row can be accurately referenced, which is crucial for maintaining data integrity.

What are foreign keys and how do they relate to primary keys?

Foreign keys are fields in one table that link to primary keys in another table. They establish a relationship between the two tables, ensuring that data remains consistent across the database.

Are there any other constraints that help maintain data integrity?

Yes, other constraints include UNIQUE constraints, which ensure all values in a column are different, and CHECK constraints, which enforce specific conditions on data values.

How can I implement these constraints in SQL?

You can implement constraints in SQL using the CREATE TABLE statement or ALTER TABLE statement. For example, you can define a primary key with PRIMARY KEY (column_name).