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Database Structures and Querying Flashcards
CompTIA DataX DY0-001 (V1) Flashcards
| Front | Back |
| What are database constraints | Rules enforced on data to ensure accuracy and consistency. |
| What character is typically used to denote wildcards in SQL LIKE queries | %. |
| What does SQL DISTINCT keyword do | Removes duplicate values in the result set. |
| What does SQL stand for | Structured Query Language. |
| What does the SQL clause WHERE do | Filters records based on a specified condition. |
| What does the SQL command DELETE do | Removes data from a table. |
| What does the SQL command INSERT do | Adds new rows to a table. |
| What does the SQL command SELECT do | Retrieves data from a table. |
| What does the SQL command UPDATE do | Modifies existing data in a table. |
| What does the SQL GROUP BY clause do | Aggregates data based on specified columns. |
| What does the SQL HAVING clause do | Applies conditions to groups created by GROUP BY. |
| What is a composite key in a database | A key consisting of two or more columns that uniquely identify a record. |
| What is a data warehouse | A central repository for storing large volumes of business data for analysis. |
| What is a foreign key in a database | A field in one table that links to the primary key in another table. |
| What is a non-relational database | A database that stores data in formats other than tables, such as documents or key-value pairs. |
| What is a normalized database | A database structured to reduce redundancy and improve data integrity. |
| What is a primary key in a database | A unique identifier for a record in a table. |
| What is a stored procedure in SQL | A set of SQL statements stored in the database to perform a specific task. |
| What is ACID compliance in databases | Ensures Atomicity, Consistency, Isolation, and Durability for transactions. |
| What is database denormalization | Adding redundancy to a database for performance improvement. |
| What is the difference between INNER JOIN and OUTER JOIN | INNER JOIN retrieves matching rows from both tables; OUTER JOIN retrieves matching rows plus non-matching rows from one or both tables. |
| What is the difference between OLTP and OLAP | OLTP handles transaction-focused tasks; OLAP is used for analytics and complex queries. |
| What is the difference between structured data and unstructured data | Structured data is organized in tables; unstructured data lacks a pre-defined format. |
| What is the purpose of a transaction in a database | Ensures that a sequence of operations is completed entirely or not at all. |
| What is the purpose of an index in a database | To speed up the retrieval of data. |
| What is the purpose of database schemas | Define the structure and rules of data storage within a database. |
This deck focuses on database design, data querying using SQL, and understanding relational and non-relational database systems.