Column (Database)
In the context of databases, a column is a vertical structure within a table that holds data for a specific attribute or field of each record. Each column is designed to hold data of a specific data type, such as integer, text, or date. For instance, in a users table, there could be columns for user_id, username, email, and date_of_birth, where each column represents a different characteristic of the users stored in the database. Each record in the table will have a value for every column, making it essential for defining the attributes of an entity.
https://en.wikipedia.org/wiki/Column_(database)
The organization of columns in databases facilitates efficient data storage and retrieval. Since each column is defined by a data type, it helps the database management system (DBMS) to enforce consistency and integrity. For example, a column defined as integer will not accept non-numeric values, ensuring that only valid data is stored. This structure also aids in optimizing queries and improves the performance of data retrieval. In relational databases, the design of columns plays a critical role in ensuring that data is organized and accessed efficiently for various use cases, from simple searches to complex data analysis.
https://www.ibm.com/docs/en/db2/11.5?topic=concepts-columns-tables
Columns also play a key role in data normalization, a process used to reduce redundancy and dependency in databases. During normalization, columns are often distributed across multiple tables to ensure that each column holds atomic values, representing the smallest unit of meaningful data. By splitting data across different columns and tables, databases can be more efficient in handling updates, deletions, and insertions. For example, instead of storing a full address in a single column, a database might store the street, city, and postal code in separate columns, reducing redundancy and improving data consistency.
https://en.wikipedia.org/wiki/Database_normalization
- Snippet from Wikipedia: Column (database)
In a relational database, a column is a set of data values of a particular type, one value for each row of a table. A column may contain text values, numbers, or even pointers to files in the operating system. Columns typically contain simple types, though some relational database systems allow columns to contain more complex data types, such as whole documents, images, or even video clips. A column can also be called an attribute.
Each row would provide a data value for each column and would then be understood as a single structured data value. For example, a database that represents company contact information might have the following columns: ID, Company Name, Address Line 1, Address Line 2, City, and Postal Code. More formally, a row is a tuple containing a specific value for each column, for example: (1234, 'Big Company Inc.', '123 East Example Street', '456 West Example Drive', 'Big City', 98765).