602 First Normal Form (1NF) PDF

602 First Normal Form (1NF) * * The First Normal Form (1NF) is the first step in the normalization process. ==** ** **...

602 First Normal Form (1NF) * * The First Normal Form (1NF) is the first step in the normalization process. ==** ** ** ** == It enforces the rule that each attribute in a table should contain only atomic (indivisible) * * ** ** * * == values , ensuring that there are no repeating groups or arrays within a column. == *** *** ~~ ~~ In other words, 1NF requires that ** ** == each cell in a table contains only a single value , and *** *** * * == == each row represents a unique record. *** *** * * == Requirements of 1NF To satisfy the requirements of 1NF: ** ** 1. Each column should contain only atomic values (no arrays or lists). == == *** *** ~~ ~~ 2. Each column should store values of a single data type. == == 3. All entries in a column should be unique for each row , without repeating groups. == == *** *** ~~** **~~ ~ Definition: A repeating group means storing multiple values in the same field ~ ** ** * * * * *** or having multiple columns for the same kind of data. *** * * * * To meet 1NF, you flatten the data by breaking it into separate rows. ** ** * * * * * * * Example 1: Student Contact Information * * * ** Student_ID ** ** Name ** ** Contact_Number ** ** Course ** 101 Alice Smith 123-456-7890 , 098-765-4321 == == Math  102 Bob Johnson 234-567-8901 Science 103 Carol White 345-678-9012 , 543-210-6789 == == History In this table: The Contact_Number column contains multiple phone numbers ` ` ==* * == == separated by commas , violating the rule of atomicity. == * * == ** **== ⠀ * Converting to 1NF * ** Student_ID ** ** Name ** ** Contact_Number ** 101 Alice Smith 123-456-7890 101 Alice Smith 098-765-4321 102 Bob Johnson 234-567-8901 103 Carol White 345-678-9012 103 Carol White 543-210-6789 Now, each cell contains only one value , satisfying the requirements of 1NF. *** *** ==* * == ** ** Each contact number has its own row , ** ** == *** ***== ensuring data is atomic and * * each record is unique. * * * Example 2: Student Course Enrollment * * * ** Student_ID ** ** Name ** ** Courses ** 101 Alice Smith Math , Science== ==  102 Bob Johnson History 103 Carol White Math , History , Science == == == == ** In this case: ** The Courses column contains multiple values separated by commas , which violates ` ` == == the 1NF rule of atomicity. ==** ** ** **== Converting to 1NF ** Student_ID ** ** Name ** ** Course ** 101 Alice Smith Math 101 Alice Smith Science 102 Bob Johnson History 103 Carol White Math 103 Carol White History 103 Carol White Science * After normalization: * * Each Course value now occupies its own row , eliminating repeating groups. == == ~~ ~~ * * Each row represents a unique record , and each cell contains only one atomic value. == == == == * * In 1NF, tables are restructured to ** ** == ensure each attribute contains only atomic values , and there are ** **== ** no repeating groups within a table. ** ~~** **~~ * By converting tables to 1NF, we * ** ** reduce data redundancy, ~~** **~~ improve data integrity, and lay a foundation for further normalization steps. * In the next lesson, we’ll cover Second Normal Form (2NF), which builds on 1NF by addressing ** ** partial dependencies and ensuring full functional dependency on the primary key.