DAB102 MySQL Check Table Maintenance PDF
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Uploaded by WondrousNewOrleans
St. Clair College
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Summary
This document provides notes on information management, specifically focusing on table maintenance in MySQL using the ALTER TABLE and CHECK TABLE commands. It illustrates various scenarios for modifying table structures and optimizing database performance.
Full Transcript
Why would you use the ALTER TABLE command in MySQL Workbench, and what are some common scenarios where it is applied? 2. What are some common scenarios where the ALTER TABLE command is applied? - **Adding new columns to accommodate new data requirements.** - **Modifying column data types...
Why would you use the ALTER TABLE command in MySQL Workbench, and what are some common scenarios where it is applied? 2. What are some common scenarios where the ALTER TABLE command is applied? - **Adding new columns to accommodate new data requirements.** - **Modifying column data types or constraints for better data integrity or performance.** - **Dropping unnecessary columns to reduce storage or simplify the table structure.** - **Adding or dropping indexes to improve query performance.** - **Adding or dropping constraints to enforce data integrity rules.** - **Renaming columns or changing table engines.** - **Partitioning tables to manage large datasets more efficiently.\ ** 3. How would alter the employees table in the HR database given the following scenarios? Table: employees ------------------ -------------- --------------------------------- **Field** **Type** **Description** emp\_id INT Primary key, unique identifier department\_id INT Employee's department number name VARCHAR(255) Employee\'s full name date\_of\_birth DATE Employee\'s date of birth gender VARCHAR(10) Employee\'s gender contact\_info VARCHAR(255) Employee\'s contact information address VARCHAR(255) Employee\'s address A\) Recent changes in data requirements that necessitate adding a new column to the table? Ex. **ALTER TABLE table\_name CHANGE old\_column\_name new\_column\_name new\_datatype;** Ex. A**LTER TABLE table\_name ADD CONSTRAINT constraint\_name PRIMARY KEY (column\_name);** Ex. **ALTER TABLE employees ADD CONSTRAINT fk\_department FOREIGN KEY (department\_id) REFERENCES departments(id);** 4. Why do we use the CHECK TABLE command in MySQL Workbench, and what does it do? 5. What is the purpose of optimizing a table in MySQL Workbench, and when should it be performed?
