Data-Management-Foundations Exam Dumps : WGU Data Management – Foundations Exam

AFull Join (FULL OUTER JOIN)selectsall records from both tables, filling in NULL values where there is no match. This ensures that no data is lost from either table.

Example Usage:

sql

SELECT Employees.Name, Departments.DepartmentName

FROM Employees

FULL OUTER JOIN Departments ON Employees.DeptID = Departments.ID;

This query retrievesall employees and all departments, even if an employeehas no assigned departmentor a departmenthas no employees.

Types of Joins:

FULL OUTER JOIN (Correct Answer)→ Includesall rows from both tables, filling missing values with NULL.

LEFT JOIN (Incorrect)→ Includesall rows from the left tableandmatching rows from the right table.

RIGHT JOIN (Incorrect)→ Includesall rows from the right tableandmatching rows from the left table.

CROSS JOIN (Incorrect)→ Produces aCartesian product(each row from one table is combined with every row from another table).

Thus, the correct answer isFULL JOIN, whichensures that all rows from both tables appear in the result.

In SQL,literalsrepresent explicit values such asnumbers, strings, or binary datadirectly written into queries. For example:

SELECT * FROM Employees WHERE Salary > 50000;

Here, 50000 is anumeric literal.

Option A (Correct):Literalsare explicit values used in SQL queries, such as 123, 'John Doe', and TRUE.

Option B (Incorrect):Commentsare non-executable text used for documentation within SQL code, typically denoted by -- or /* ... */.

Option C (Incorrect):Identifiersare names oftables, columns, or other database objects, such as EmployeeID.

Option D (Incorrect):Keywordsare reserved words in SQL (e.g., SELECT, FROM, WHERE) that define operations and syntax.

TheALTER TABLEstatement is used to modify an existing database table structure. One common clause isCHANGE, which allows renaming a column and modifying its data type.

Example:

sql

ALTER TABLE Employees CHANGE COLUMN OldName NewName VARCHAR(50);

Option A (Incorrect):DELETE is used to removerows, not alter table structure.

Option B (Correct):CHANGE is avalid clausefor renaming and modifying columns in MySQL and some other databases.

Option C (Incorrect):STOP is not a valid SQL keyword for altering tables.

Option D (Incorrect):AGGREGATE refers to functions like SUM() and AVG(), not table alterations.