Final answer:
A column that has equivalent data existing in two or more tables is called a foreign key. It establishes a relationship between tables and ensures data consistency.
Step-by-step explanation:
In the context of databases, a column that has equivalent data existing in two or more tables is called a foreign key. A foreign key is a column that establishes a relationship between tables by referencing the primary key of another table. It is used to maintain referential integrity and ensure data consistency in relational databases.
For example, consider two tables: 'Books' and 'Authors'. The 'Books' table may have a foreign key column named 'Author_ID', which references the primary key column 'Author_ID' in the 'Authors' table. This allows the 'Books' table to link each book to its corresponding author.
By utilizing foreign keys to connect related tables, it becomes possible to retrieve and manipulate data from multiple tables simultaneously, enabling more complex queries and data analysis.