D426 Data Management Foundations - Set 1 - Part 2

Correct Answer: Multiple columns

A composite primary key is made up of two or more columns in a table, and together these columns uniquely identify each row.

Correct Answer: FULL JOIN

A FULL JOIN selects all rows from both tables, regardless of whether there is a match, filling in NULLs where necessary.

Correct Answer: Hash Index

A Hash Index assigns index entries to buckets using a hash function, which computes a bucket number from the value of the indexed column.

Correct Answer: Groups rows that have the same values in specified columns

The GROUP BY clause groups rows that have the same values in specified columns, often used with aggregate functions like SUM() or COUNT().

Correct Answer: DROP TABLE

The DROP TABLE command removes an entire table, including its rows and structure, from the database.

Correct Answer: LIKE

The LIKE operator is used for pattern matching in SQL, often with wildcard characters such as '%' for multiple characters or '_' for a single character.

Correct Answer: UPDATE

The UPDATE statement is used to modify the data in existing rows in a table by specifying new values for the columns.

Correct Answer: CREATE INDEX

The CREATE INDEX command creates an index on one or more columns of a table to improve the speed of data retrieval operations.

Correct Answer: LIMIT

The LIMIT clause is used to specify the maximum number of rows to be returned by a SELECT query, limiting the result set.

Correct Answer: The structure of a database, including tables, columns, and relationships

The schema of a database defines its structure, including the tables, columns, data types, and relationships between tables.

Correct Answer: DISTINCT

The DISTINCT operator returns only unique values from a column, removing any duplicate values from the result set.

Correct Answer: Foreign Key

A Foreign Key is used to refer to the primary key in another table, establishing a relationship between the two tables.

Correct Answer: To ensure that values in a column follow a specific rule

A CHECK constraint ensures that values in a column must satisfy a specified condition or rule, enforcing data integrity.

Correct Answer: Third Normal Form (3NF)

A table is in Third Normal Form (3NF) when all columns are functionally dependent on the primary key and there are no transitive dependencies between non-key columns.

Correct Answer: DELETE

The DELETE statement is used to remove specific rows from a table based on a condition specified in the WHERE clause.

Correct Answer: WHERE

The WHERE clause filters rows before they are grouped in a GROUP BY query, applying conditions to individual rows.

Correct Answer: Primary Key

The Primary Key uniquely identifies each row in a table and ensures that no two rows have the same value in the primary key column(s).

Correct Answer: To modify the structure of an existing table

The ALTER TABLE command is used to change the structure of an existing table, such as adding, removing, or modifying columns.

Correct Answer: RIGHT JOIN

A RIGHT JOIN includes all rows from the right table and only the matching rows from the left table. Rows from the right table without a match in the left table will still appear in the result.

Correct Answer: Functional Dependence

Functional Dependence occurs when one column's value is determined by another column's value in a database table.