First Normal Form (1NF)

First Normal Form (1NF) is the most basic level of normalization and a fundamental requirement for any relational database table. A table is said to be in 1NF if it satisfies two main conditions. First, each cell of the table must contain a single, atomic (indivisible) value. This means you cannot have lists or multiple values stored in a single cell. For example, a 'phone_numbers' column containing '555-1234, 555-5678' would violate 1NF. To comply, you would need to create a separate table for phone numbers, linking it back to the original table with a foreign key, or have separate columns like 'phone1' and 'phone2' (though the separate table approach is usually better). Second, each record (row) in the table must be unique, which is typically achieved by having a primary key. This rule ensures that there are no duplicate rows. Essentially, 1NF sets the basic ground rules for a well-structured table: organize data into rows and columns, eliminate repeating groups of data by creating separate tables for related data, and identify each set of related data with a primary key. While meeting 1NF is a necessary first step, it doesn't solve all redundancy issues, which is why higher normal forms are needed. However, without satisfying 1NF, a table isn't even considered a true relational table.