SQL Server Database - Glossary

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Atomicity, Consistency, Isolation, and Durability.
A database object that defines what actions will be taken when a specific event occurs.
Also known as Binary Tree, this is a system of storing hierarchical information that is used for fast searching. A B-Tree can be modeled as a triangular shape. The smallest part of the triangle is known as the root node. The search starts from this node. Each root node points to ranges of values on other nodes, known as decision nodes. Each decision node can point to other decision nodes or the largest part of the triangle, called the leaf node. Each step along the way will narrow the search until the final leaf node is reached.
Clustered index
An index that stores data physically on the disk in order, based on the primary key.
Multiple columns that are grouped together for a specific purpose, such as a primary key or an index.
Composite index
An index by where multiple keys are used in the index, not only a single key.
A method used by SQL Server to enforce data integrity. Constraints will automatically check integrity when data is inserted, updated, or deleted.
Method by which SQL Server enforces data integrity. Constraints will automatically check the integrity when data is inserted, updated, or deleted
Covered query
A select query by where all columns selected are contained within an index.
data integrity
A term used to describe the quality (in terms of accuracy, consistency, and validity) of data in a database, in the sense that values required to enforce data relationships actually exist. Problems with data integrity occur when a value in one table that’s supposed to relate to a value in another can’t, because the second value either has been deleted or was never entered.
The specification for the type of data a column is to represent.
A situation that occurs when two processes are dependent on each other, resulting in an impass.
A database object that is used to insert a value into a column with which the default is bound, in case the value is omitted in a Transact-SQL statement.
Distributed transaction
A SQL Server 7 transaction in which data is distributed across multiple SQL Server.
Domain integrity
Validates that each database column has valid values. Oftentimes used to help enforce business rules.
A single stand-alone unit or a business object about which data are stored in a database; usually synonymous with a database table.
Entity integrity
A condition relating to the quality of data in a table, in which every row is unique and every row can be pinpointed and accessed without involving any other row.
Code that runs automatically when certain conditions exist.
One or more files that are grouped together for ease of database administration.
The process of running code when an event occurs.
Foreign key
One or more columns in a table whose values match the values in the primary key of another table. Used by SQL Server to enforce referential integrity.
A forward-only cursor allows movement in a forward direction only.
A global scope makes a variable available throughout an entire process.
Globally Unique Identifier.
A SQL Server 7 term used to indicate that unique values are automatically generated for each and every row of data that is inserted into a table.
Identity Flag
An identity flag is an attribute that ensures that values in a column are automatically incremented and unique within the column
Database object used to speed-up queries.
Isolation level
One of the four levels that determine how effectively SQL Server will allow multiple users to make concurrent changes to data. The highest level of concurrency (serializable) uses the most resources. The lowest level of concurrency (Read uncommitted) uses the leastresources.
A database object that defines steps that are to be performed at specific time intervals.
A local scope makes a variable available only to the procedure where it was created.
Logical data model
Logical data model-representation of your database in groups of entities after applying the appropriate level ofnormalization.
The actual records that make up a recordset in a cursor.
A nested process or procedure is buried within another. Most processes or procedures can contain multiple nesting levels, but areconstrained by a limit. This limit is based on the type of nesting.
Non-clustered index
Indexes that simply "point" to where the data is physically located, thereby speeding up queries.
An individual that can be notified by alerts.
Optimistic locking
This locking scheme is used when it is assumed that no other user will change data after you read it and before you save it.
Pessimistic locking
This locking scheme is used when it is assumed that a user will change data between the time that you read it and save it.
Physical data model
The actual physical representation of your database as it maps to database objects and operating system files.
An attribute of decimal and numeric datatypes that specifies the number of decimal places to the left and right of the decimal point.
Primary key
A column whose values uniquely identify a row in a table.
Relational integrity
Guaranteeing the quality of data between tables in a database by enforcing the relationships between those tables.
Result set
The rows of data that a query returns.
An attribute of numeric datatypes that specifies the number of decimal places to the right of the decimal point.
The length of time that a variable is available.
Movement through a recordset on a record-by-record basis, similar to the way you scroll through text in a computer document.
Spool operation
In SQL-Server, a "spool operation" is when SQL Server has to save a temporary set of data.
Table scan
The query optimizer reads the complete contents of a table, instead of using an index.
A period of time, usually measured in seconds, in which a given.process attempts to complete. If the process doesn't complete within the allotted period of time, the process aborts with an error and "times-out".
A visual representation of the performance of certain events.
"A transaction is a single unit of work that either succeeds or fails as a unit, regardless of the number of steps involved or the number of participants in the transaction. Transactions initiated by an Active Server Page script are managed by Microsoft Transaction Server (MTS)."
Transaction log
A database file where temporary transaction data is stored so that the data can be rolled back if a transaction fails.
Two-phase commit
Aprocess used by distributed transactions to successfully roll back or commit transactions over multiple computers. This is done in two phases, prepare and commit.
Unique key
One or more columns that cannot contain duplicate data in a table. Similar to a primary key, except that it doesn’t have to uniquely identify a row of data.

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