Understanding MySQL Primary Keys

MySQL Primary Key

 

A primary key is an important concept in MySQL and other relational databases. In MySQL, a primary key is a unique identifier for each record in a database table. It ensures data integrity by ensuring that each record can be uniquely identified by its primary key.

 

A primary key is a column or set of columns that uniquely identifies a record in a database table. A primary key is often a single column that contains a unique value for each row in the table. This value must be unique and cannot be changed. It is also used to identify a record when performing lookups or updates.

 

In MySQL, a primary key can be either a single column or a combination of two or more columns. A single column primary key is called a simple primary key. A combination of two or more columns is called a compound primary key.

 

When creating a table, you must specify which column or columns will be the primary key. To do this, you use the CREATE TABLE statement and specify the PRIMARY KEY clause. This clause specifies the name of the primary key column or columns.

 

Primary keys are used to enforce data integrity. They ensure that each record in a table is unique and can be identified by its primary key. They also help to ensure that data is not duplicated in the table.

 

Primary keys can also be used to create relationships between tables. For example, a foreign key is a column in one table that references the primary key of another table. This allows you to create relationships between tables and ensure data integrity.

 

In summary, a primary key is an important concept in MySQL and other relational databases. It is a unique identifier for each record in a database table and is used to enforce data integrity and create relationships between tables.