VA: SQL Intermediate: Data Manipulation Language (DML) скачать в хорошем качестве

VA: SQL Intermediate: Data Manipulation Language (DML)

Since we are focusing on conceptual mastery and code-based examples rather than a live lab environment, this module provides the logic and syntax needed to manipulate healthcare data safely. You will learn how to transition from building a "filing cabinet" (DDL) to managing the "papers" inside (DML). 1. DML vs. DDL: While DDL defines the structure of your tables, DML is used specifically to modify the data rows within those structures. 2. The INSERT Statement: Used for adding new data, such as a new patient registration or a lab result, with a focus on matching column order and data types. 3. The UPDATE Statement: Used to modify existing data, such as updating a patient's phone number or changing an encounter status from "arrived" to "completed". 4. The DELETE Statement: Used to remove rows. In a healthcare context, we often prefer "Soft Deletes" (updating a status to 'Inactive') over "Hard Deletes" to preserve audit trails for HIPAA compliance. 5. The WHERE Clause Safety Net: A critical concept for both UPDATE and DELETE; without a WHERE clause, the command will affect every single row in the table. 6. Transactional Integrity: Learn how to group multiple commands (like registering a patient and their initial encounter) using BEGIN, COMMIT, and ROLLBACK to ensure data remains consistent.