The role of PRIMARY KEYS in SQL databases is fundamental for maintaining data integrity and efficient data management. These unique identifiers prevent duplicate records and support relational database design by linking tables through FOREIGN KEY constraints. PRIMARY KEYS must be unique and non-null, with INTEGER, CHAR, VARCHAR, and UUID as common data types. They are essential in data modeling and complex query execution, underpinning the structure of relational databases.
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PRIMARY KEYS are unique identifiers for each record in a database table
Preventing Duplicate Records
PRIMARY KEYS prevent duplicate records in a database table
Efficient Data Retrieval
PRIMARY KEYS enable efficient data retrieval in a database table
PRIMARY KEYS form the basis for relational database design by linking tables through FOREIGN KEY constraints
PRIMARY KEYS enforce rules of uniqueness and non-nullability in a database table
Commonly Used Data Types
INTEGER, CHAR, VARCHAR, and UUID are commonly used data types for PRIMARY KEYS
Auto-increment Feature
PRIMARY KEYS can have an auto-increment feature for ease of management
Defining PRIMARY KEYS is a fundamental step in designing a database, and it involves choosing columns and data types and designating a PRIMARY KEY using the `CREATE TABLE` SQL statement
PRIMARY KEY constraints can be declared within the column definition or separately using the CONSTRAINT keyword
A column with consistently unique and non-null values should be chosen as the PRIMARY KEY
Modifying an existing PRIMARY KEY requires dropping the current constraint and defining a new PRIMARY KEY constraint on the appropriate column(s)
PRIMARY KEYS and FOREIGN KEYS are essential for defining relationships between tables in a relational database
FOREIGN KEYS reference PRIMARY KEYS in other tables, ensuring referential integrity
Tables with PRIMARY KEYS must be established first, followed by adding FOREIGN KEY columns and defining constraints to create relationships between tables
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PRIMARY KEY uniqueness
A PRIMARY KEY must hold unique values, ensuring each row in a table is distinct.
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PRIMARY KEY vs FOREIGN KEY
PRIMARY KEY uniquely identifies records within its own table, while FOREIGN KEY links to a PRIMARY KEY in another table.
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PRIMARY KEY role in data integrity
PRIMARY KEY prevents duplicate records, maintaining the uniqueness and reliability of the database.
