SQL Fundamentals Quiz

SQL Clauses and Operations

• The HAVING clause filters the rows after grouping.
• The OUTER JOIN operation includes tuples from one table even if there's no match in the other table.
• The LEFT OUTER JOIN operation includes tuples from the left table even if there's no match in the right table.
• The FULL OUTER JOIN operation includes tuples from both tables even if there's no match in the other table.

Working with NULL Values

• SQL treats NULL values as unknown in comparisons.
• NULL values are not treated as 0 or ignored completely.

Join Operations

• The INNER JOIN operation combines data from two tables based on a common attribute.
• The OUTER JOIN operation includes tuples from one table even if there's no match in the other table.
• The RIGHT OUTER JOIN operation is similar to the LEFT OUTER JOIN, but includes tuples from the right table.

Retrieving Data

• The OUTER JOIN operation is used to retrieve data from one table that might not have matching records in another table.
• The DISTINCT keyword eliminates duplicate values from the result set.

Inserting, Updating, and Deleting Data

• The INSERT command is used to insert a new tuple into a relation.
• The UPDATE command is used to update existing data in a table.
• The DELETE command is used to delete a tuple from a relation.

Pattern Matching

• The LIKE operator is used for pattern matching on strings.
• The % symbol is used to match any sequence of characters, and the _ symbol is used to match any single character.

Ordering and Grouping

• The ORDER BY clause is used to specify the ordering of results.
• The DESC keyword is used to specify descending order.
• The GROUP BY clause is used to group the results based on a common attribute.
• The HAVING clause filters the rows after grouping.

Relations and Tuples

• A relation is informally described as resembling a table of values.
• Rows in a relation are called tuples.
• The key of a relation is a value uniquely identifying a row.
• The schema of a relation denotes the table's header.
• A tuple in the context of a relation is an ordered set of values.

Integrity Constraints

• The primary key attribute ensures that no two tuples have the same value.
• Referential integrity constraints enforce data consistency between related tables.
• The entity integrity constraint ensures that each tuple has a unique identifier.
• The domain constraint defines the format of attribute values.