Question

What are the columns in a table assigned in SQL?

1) Data types
2) Primary keys
3) Foreign keys
4) Constraints

Answer 1

In SQL, columns in a table can have data types, primary keys, foreign keys, and constraints, which define the allowed data, uniqueness, relationships, and rules for the columns.

Step-by-step explanation:

In SQL, the columns in a table can be assigned various attributes and constraints to define the data they hold. These include:

• Data types: Specify the kind of data that can be stored in the column, such as INTEGER, VARCHAR, DATE, etc.
• Primary keys: A column or a set of columns used to uniquely identify rows in the table.
• Foreign keys: A column or set of columns in one table that uniquely identifies a row of another table or the same table.
• Constraints: Rules applied to the data in the column, such as NOT NULL, UNIQUE, CHECK, or FOREIGN KEY.

These elements ensure data integrity and define the relationships between tables within the database.