Entity Relationship Model Quiz

• A Primary Key is a column or group of columns that uniquely identifies a row in a database.
• A constraint is a rule that governs allowable values in a database based on relational and business rules.
• A check constraint specifies an expression on one or more columns that is violated when the expression is false and satisfied when the expression is true or null.
• The LIKE operator performs pattern matching and can be case-insensitive or case-sensitive.
• HAVING is used with GROUP BY to filter results.
• UNION combines two query results into one table.
• An equijoin is a join where the join condition is an equality condition.
• A correlated subquery is a subquery whose WHERE clause references a column from the outer query.
• Flattening is the process of replacing a subquery with an equivalent join.
• A base table is the table specified in the view query's FROM clause.
• A query execution plan converts a SQL query into a sequence of low-level database actions.
• Entity-Relationship modeling is a high-level representation of data requirements.
• A reflexive relationship is a relationship between an entity and itself.
• Cardinality refers to the maxima and minima of relationships and attributes.
• An identifying attribute is a singular, required attribute used to identify an entity.
• A subject area is a group of related entities from a complex model.
• An artificial key is a column or group of columns used as a primary key when no suitable natural key exists.
• Dependency is a relationship between columns where one column depends on another.
• Normal forms are rules for designing tables with less redundancy.
• Volatile memory is memory that is lost when disconnected from power.
• Main memory, also known as random-access memory, is the primary memory used when computer programs execute.
• Flash memory is less expensive and higher capacity than main memory, and it groups data in pages.
• A magnetic disk, also known as a hard-disk drive, is used to share large amounts of data and groups data in sectors.
• Row-oriented storage stores an entire row in one block, while column-oriented storage stores values for a single column only.
• A hash function, such as a modulo function, is used to distribute data evenly across a database.
• Dynamic hash functions automatically allocate more blocks and buckets as needed and distribute rows across all buckets.
• Table clusters interleave rows of two or more tables in the same storage area.
• A single-level index is a file containing column values and pointers to rows containing the column value.
• A multi-column index is an index that contains composite values from all indexed columns.
• A fan-out index is a multi-level index that has a fixed number of index entries per block.
• The branch block is the bottom level of a B-Tree, where all indexed values appear.
• A shard is a subset of table data, usually a subset of rows, stored on different computers in a distributed database.
• A slow query log records all long-running queries submitted to the database.
• A query parser checks queries for syntax errors and converts valid queries to an internal representation.
• A consistent database conforms to all rules at all times.
• A network partition occurs when nodes in a database cannot communicate due to a network error.
• A partition-tolerant database continues to function when a network partition occurs.
• Storage arrays manage replicas internally, without database intervention.
• Type 2 design for slowly-changing dimensions involves adding start and end foreign keys to the fact table.
• An autonomous database operates independently of other participating data sources.
• Heterogeneous databases either run under different database systems or have incompatible schemas.
• A global catalog is a directory of participating database objects such as tables, columns, and indexes.
• Database wrappers convert decomposed queries to the appropriate syntax for each participating database.
• A federated database user mapping associates a federated database user with a participating database user.

Test your knowledge of entity relationship model concepts with this quiz! Topics covered include entity instances, weak entities, strong entities, and subtype entities.