Database Operations Quiz

A relational operation that combines two union-compatible relations by including all tuples from both relations without duplicates.

Two relations are union-compatible when they have the same number of attributes and the corresponding attributes have the same data type.

An operation that returns tuples present in the first relation but not in the second relation. Both relations must be union-compatible.

The Projection operation selects specific attributes from a relation and eliminates duplicate tuples.

The process of making two relations union-compatible by applying the Projection operation, selecting the same attributes from both relations.

A collection of tuples, representing data organized into columns (attributes) and rows (tuples).

An attribute or column in a relation.

A row in a relation, representing a record or data instance.

A condition or criteria used to filter rows in a table (relation), selecting only those rows that meet the specified condition.

A relational algebra operation that contains only the rows present in both of the given tables (relations).

A relational algebra operation that combines every row from one table (relation) with every row from another table (relation), creating a new table with all possible combinations.

A relational algebra operation that removes duplicate rows from a table (relation).

A type of join operation that keeps all tuples from the left-hand relation in the result. If no corresponding tuple is found in the right-hand relation, the attributes from the right-hand relation will be filled with nulls.

A type of join operation that keeps all tuples from the right-hand relation in the result. If no corresponding tuple is found in the left-hand relation, the attributes from the left-hand relation will be filled with nulls.

A type of join operation that keeps all tuples from both the left-hand and right-hand relations in the result. If no corresponding tuple is found in the other relation, the missing attributes will be filled with nulls.

A join operation that performs a regular join and then only projects the attributes of the first operand. This reduces the number of tuples needed to form the join.

An operation that preserves all information from the joined relations. It achieves this by keeping tuples that would have been lost in other kinds of joins, filling the missing values with nulls.

A function that compares and combines information from two tables based on matching values in a common column.

The process of selecting and extracting data from a database.

A structured set of data organized in rows and columns.

A relational algebra operation that groups tuples based on common attribute values and applies aggregate functions like COUNT, SUM, MIN, MAX, or AVERAGE to produce summary information. It's similar to using the GROUP BY clause in SQL.

A function in relational algebra that calculates the number of rows or tuples in a relation. It's used to determine the count of elements within a group or in a dataset.

A function in relational algebra that calculates the sum of all values in a column or attribute. It's used to find the total value for a specified attribute in a group or dataset.

A function in relational algebra that finds the smallest value within a column or attribute of a relation. It helps to identify the minimum value in a set of data.

A function in relational algebra that finds the largest value within a column or attribute of a relation. It helps to identify the maximum value in a set of data.

A function in relational algebra that calculates the average of all values within a column or attribute of a relation. It helps determine the central tendency of a set of data.

Attributes of a relation that are used to group tuples during a grouping operation. These attributes determine the criteria for grouping tuples together.

A list of Aggregate Functions (AL) that are applied to a group of tuples during a grouping operation. These functions provide summary information about the grouped data.

A variable in tuple relational calculus that takes values from a specific relation, representing a tuple from that relation. It's like a placeholder for a row in a table.

A set of tuples that satisfy a particular condition or formula described by a predicate. It's like selecting specific rows from a table based on a set of criteria.

A logical expression that defines a condition or a rule for selecting tuples. It's like a filtering rule for data in a database.

A logical expression, or a combination of smaller expressions, that defines a condition on one or more predicates, describing the query for retrieving tuples.

A powerful way to retrieve information from relational databases by defining predicates and formulae that describe the tuples to be retrieved.

The process of determining the attribute value for a specific tuple variable by referencing the attribute name within the tuple variable. It's like picking a specific value from a row.

A mathematical tool used to denote the existence or non-existence of a tuple that satisfies a given predicate.

Using quantifiers to express the existence or non-existence of tuples that satisfy a given predicate. This allows you to define more complex selections based on how many rows meet a condition.

The existential quantifier "$\exists$" (there exists) is used in formulae that must be true for at least one instance. It asserts the existence of at least one element that satisfies a specific condition.

The universal quantifier "$\forall$" (for all) is used in statements that must be true for every instance. It asserts that every element in a set satisfies a specific condition.

De Morgan's laws applied to quantifiers establish equivalences for negating statements involving existential and universal quantification.

A tuple variable is called a bound variable when it's qualified by "$\forall$" or "$\exists$". A tuple variable that is not qualified by a quantifier is called a free variable.

In relational calculus expressions, only free variables should appear on the left side of the '|' symbol. This implies that the resulting set of tuples will have the same attributes as defined by the free variables.

Relational calculus expressions, like sentences in natural language, must follow specific rules to be unambiguous and make sense.

A well-formed formula in relational calculus is a sequence of symbols that represents a logical statement. It must satisfy specific structural requirements.