- What is a database?
A database is an organized collection of data stored and accessed electronically. It is designed to allow efficient storage, retrieval, and manipulation of large amounts of data.
- What is a database management system (DBMS)?
A database management system (DBMS) is a software program that allows users to create, define, and manipulate a database. It also allows users to control access to the database, to ensure that data is secure and to ensure that data is stored in a consistent and orderly manner.
- What is a database schema?
A database schema is a set of rules that specifies the structure of a database. It defines the tables, fields, data types, and other objects that make up a database, as well as the relationships between these objects.
- What is SQL?
SQL (Structured Query Language) is a programming language used to communicate with relational databases. It is used to create, modify, and query databases.
- What is a primary key?
A primary key is a field or group of fields in a database table that uniquely identifies each record. It is used to ensure the integrity of the data, as it ensures that no two records in the table have the same primary key value.
- What is a foreign key?
A foreign key is a field or group of fields in a database table that refers to the primary key of another table. It is used to establish a relationship between two tables, and to ensure the integrity of the data by preventing the creation of records that do not have a corresponding foreign key value in the related table.
- What is normalization?
Normalization is the process of organizing a database in a way that reduces redundancy and dependency. It is a systematic method of designing a database that minimizes data redundancy and dependency, and helps to ensure the integrity of the data.
- What is denormalization?
Denormalization is the process of intentionally adding redundancy to a database in order to improve performance. It is often used to speed up the performance of database queries by pre-calculating and storing data that would otherwise be calculated on the fly.
- What is an index?
An index is a data structure that allows efficient access to data in a database table. It is used to speed up the performance of queries by providing a faster way to locate data in a table.
- What is a view?
A view is a virtual table that is created based on a SELECT statement. It does not store data itself, but rather displays data from one or more tables in a database.
- What is a trigger?
A trigger is a set of SQL statements that are automatically executed in response to a specific event, such as the insertion, deletion, or update of a record in a table. Triggers are used to enforce business rules or to perform additional actions when certain events occur in the database.
- What is a stored procedure?
A stored procedure is a pre-compiled set of SQL statements that can be called by a program or triggered by an event. Stored procedures are used to perform tasks that are frequently needed, and can be called with a single line of code. They can also accept input parameters and return output parameters.
- What is a transaction?
A transaction is a group of SQL statements that are treated as a single unit of work. If one statement in the group fails, the entire transaction is rolled back, and the database is restored to its state before the transaction began. Transactions are used to ensure the consistency and integrity of a database.
- What is a schema?
A schema is a logical grouping of database objects, such as tables, views, and stored procedures. It is used to group related objects together, and to allow multiple users to use the same objects without interfering with each other.
- What is a NoSQL database?
A NoSQL database is a database that does not use the traditional SQL relational database model. NoSQL databases are designed to handle large amounts of data that may be structured, semi-structured, or unstructured, and are often used for big data and real-time web applications. Examples of NoSQL databases include MongoDB, Cassandra, and Couchbase.
- What is a database administrator (DBA)?
A database administrator (DBA) is a person who is responsible for the design, implementation, maintenance, and performance of a database. The DBA’s tasks may include creating and maintaining database structures, backing up and restoring databases, tuning database performance, and enforcing security and integrity measures.
- What is a data warehouse?
A data warehouse is a large-scale, centralized database that is designed for efficient querying and analysis of data. It is used to store historical data from multiple sources, and is often used for business intelligence and reporting.
- What is ETL?
ETL stands for Extract, Transform, Load. ETL is a process that involves extracting data from one or more sources, transforming it to fit the needs of the target database or application, and then loading it into the target database. ETL is commonly used to move data from transactional databases to data warehouses, or to move data between different systems or formats.
- What is a data mart?
A data mart is a subset of a data warehouse that is designed to focus on a specific area of a business, such as sales or marketing. A data mart typically contains a subset of the data in a data warehouse, and is used to support specific business needs or functions.
- What is a database index?
A database index is a data structure that allows efficient access to data in a database table. It is used to speed up the performance of queries by providing a faster way to locate data in a table. An index can be created on one or more columns of a table, and can be either a clustered index or a non-clustered index.
- What is a database cursor?
A database cursor is a control structure that allows traversal over the rows of a result set from a SELECT statement. Cursors are used to process each row individually, and are often used to perform operations on the rows returned by a SELECT statement.
- What is a database transaction?
A database transaction is a group of SQL statements that are treated as a single unit of work. If one statement in the group fails, the entire transaction is rolled back, and the database is restored to its state before the transaction began. Transactions are used to ensure the consistency and integrity of a database.
- What is a database constraint?
A database constraint is a rule that is applied to a database table to ensure the integrity of the data. Constraints can be used to specify the data type, range, or format of data that can be stored in a column, or to specify the relationships between columns in a table.
- What is a database trigger?
A database trigger is a set of SQL statements that are automatically executed in response to a specific event, such as the insertion, deletion, or update of a record in a table. Triggers are used to enforce business rules or to perform additional actions when certain events occur in the database.
- What is a database partition?
A database partition is a logical division of a database table, in which each partition contains a subset of the rows of the table. Partitions can be created to improve the performance of certain types of queries, and to make it easier to manage and maintain large tables.
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