Glossary
This is an acronym for atomicity, consistency, isolation, durability. These four concepts of transactional data stores, including SQL databases, ensure data integrity.
This is the representation of all arcs or edges of a graph as a list. In SQL, this is often implemented as a self-referential table in which each row maintains a pointer to its parent node in the graph.
ADO.NET Data Services
Also known as “Project Astoria,” ADO.NET Data Services provides middle-tier support for accessing SQL Server databases through REST-style queries and entity data models (EDMs).
This is the nonrecursive query specified in the body of a CTE.
This is a well-defined interface provided by an application or service to support requests and communications from other applications.
Assembly
Asymmetric encryption
Asymmetric encryption is encryption that requires two different keys: one to encrypt data and another to decrypt it. The most common form of asymmetric encryption is public key encryption, in which the two keys are mathematically related.
Atomic data types, list data types, and union data types
Atomic data types are indivisible data types that derive from the xs:anyAtomicType type. Examples include xs:boolean, xs:date, and xs:integer. List data types are types that are constructed of sequences of other types. Union data types are constructed from the ordered union of two or more data types, or a restricted subset of a data type. The XML Schema 1.1 Part 2: Data types specification working draft (www.w3.org/TR/xmlschemall-2/#ordinary-built-ins) defines no built-in union data types.
Axis
An axis specifier indicates the relationship between the nodes selected by the location step and the context node. Examples of axis specifiers include child, parent, and ancestor.
This is a command-line utility supplied with SQL Server for the purpose of quickly loading large datasets into tables.
Certificate
A certificate is an electronic document consisting of an asymmetric key with additional metadata such as an expiration date and a digital signature that allows it to be verified by a third-party like a certificate authority (CA).
Check constraint
A check constraint is a condition placed on a table that restricts the range of valid values for one or more columns.
The CWA is a logic formalism that states what is not known to be true is false. SQL databases violate the CWA through the introduction of NULLs.
This is an index that contains a table’s row data in its leaf-level nodes.
Comment
XQuery comments are denoted by the (: and :) delimiters in XQuery queries. XQuery comments are ignored during processing. They should not be confused with XML comment nodes, which are designated with < !-- and -- > delimiters.
T-SQL allows single-line comments that begin with -- or multiline comments enclosed in /* and */ delimiters.
Computed constructors provide an alternative way to create XML nodes by specifying the type of node to be created through the use of special keywords.
Content expression
A content expression is part of a computed constructor, enclosed in braces, that generates XML node content.
This expression evaluates to the context node.
The context node is the node currently being processed. Each node of each set/sequence returned by a step in a location path is used in turn as a context node. Subsequent steps define their axes in relation to the current context node. For instance, with the sample XPath expression /Root/Person/Address, the Root node is the first context node. All Person nodes returned below Root become the context node in turn, and the Address nodes are retrieved relative to these context nodes.
Database encryption key
This is an encryption key used by Transparent Data Encryption to encrypt entire SQL Server databases.
Database master key
This is a database-level encryption key used to secure other keys in the database.
Data domain
The data domain for a column includes all valid values that may be stored in that column. The data domain can be restricted through the use of data types, check constraints, referential integrity/foreign key constraints, and triggers.
Data page
A data page is the smallest unit of storage that SQL Server can allocate. The data page consists of 8 KB of logically contiguous storage.
Datum
A geodetic datum is a set of reference points against which position can be measured. A datum is often associated with a model of the shape of the earth to define a geographic coordinate system.
An EDM is an abstract logical representation of a physical database, used to implement database connectivity in the middle or client tiers.
XEvents is a lightweight diagnostic system that can help you troubleshoot the performance problems with the SQL Server.
EKM is a SQL Server 2012 encryption option that allows you to physically store encryption keys on third-party hardware security modules (HSMs).
Extent
An extent is SQL Server’s basic allocation unit of storage. An extent is 64 KB in size and consists of eight logically contiguous data pages, each page being 8 KB in size.
ETL processes involve pulling data from disparate data sources, cleaning and scrubbing the data, manipulating it (transform), and storing it in the database.
A facet is a schema component used to constrain data types. A couple of commonly used facets are whiteSpace, which controls how whitespace in string values is handled, and length, which restricts values to a specific number of units in length.
This is a primary expression followed by zero or more predicates.
FLWOR expression
FLWOR is an acronym for the XQuery keywords for, let, where, order by, and return. FLWOR expressions support iteration and binding variables.
A foreign key constraint is a logical coupling of two SQL tables through the values of specified columns.
A full-text catalog is a logical grouping of SQL Server full-text indexes for management purposes.
Full-text index
FTS is the SQL Server 2012 implementation of SQL Server full-text search engine with the SQL Server query engine.
This is XQuery 1.0 and XPath 2.0 Functions and Operators specification, available at www.w3.org/TR/xquery-operators/.
This is an existentially quantified XQuery comparison that may be applied to operand sequences of any length. In general comparisons, the nodes are atomized and the atomic values of both operands are compared using value comparisons. If any of the value comparisons evaluate to true, the result is true.
GML is a standard for the representation of geographic data using XML.
Grouping set
A grouping set is a SQL Server 2012 feature that allows you to define sets of grouping columns in your queries.
Hash
A hash is the result of applying a mathematical function or transformation on data to generate a smaller “fingerprint” of the data. Generally, the most useful hash functions are one-way collision-free hashes that guarantee a high level of uniqueness in their results.
Heap
A heterogeneous sequence is an XQuery sequence of atomic values of different types and/or XML nodes. SQL Server XQuery does not support heterogeneous sequences consisting of atomic values and nodes.
A homogeneous sequence is an XQuery sequence consisting entirely of nodes or entirely of singleton atomic values of compatible data types.
Indirect recursion
Indirect recursion is recursion by a trigger that occurs when a trigger fires, causing another trigger of the same type to fire, which causes the first trigger to fire again.
SQL Server integrated full-text search (FTS) can search for inflectional forms of a word, including verb tenses and plural forms of nouns.
An IV is a block of bits that is used to obfuscate the first block of data during the encryption process.
LINQ adds native data source-agnostic querying capabilities to .NET languages using a declarative syntax.
Location path
A path is an XPath or XQuery expression that addresses a specific subset of nodes in an XML document. A location path is a series of steps separated by the solidus (forward slash) character, evaluated from left to right. Each step generates a sequence of items. Location paths can be relative or absolute. Absolute location paths begin with a single solidus character; relative location paths do not.
Logon triggers
Materialized path model
In the materialized path model for storing hierarchical data, the entire path to the root node is stored with each node in the hierarchy.
MARS allows you to simultaneously open multiple result sets on a single open connection.
In the nested sets model, hierarchical data is represented as a collection of sets containing other sets. The lower and upper bounds of each set define the contents of the set.
XPath 2.0 and XQuery 1.0 treat XML data as a hierarchical tree structure, similar to (but not exactly the same as) the Document Object Model (DOM) that web programmers often use to manipulate HTML and XML. XPath and XQuery XML trees are composed of the seven types of nodes defined in the W3C XQuery 1.0 and XPath 2.0 Data Model (XDM), full descriptions of which are available at www.w3.org/TR/xpath-datamodel/#node-identity. These node types include the following:
- Attribute nodes, which represent XML attributes
- Comment nodes, which encapsulate XML comments
- Document nodes, which encapsulate XML documents
- Element nodes, which encapsulate XML elements
- Namespace nodes, which represent the binding of a namespace URI to a namespace prefix (or the default namespace)
- Processing instruction nodes, which encapsulate processing instructions
- Text nodes, which encapsulate XML character content
XPath 1.0 defines the node types it uses in Part 5 of the XPath 1.0 specification. The main difference between XPath 1.0 nodes and XDM nodes is that XPath 1.0 defines the root node of a document in place of the document nodes of the XDM. Another major difference is that in the XDM, element nodes are either explicitly or implicitly (based on content) assigned type information.
Node test
A node test is a condition that must be true for each node generated by a step. A node test can be based on the name of the node, the kind of node, or the type of node.
A nonclustered index is an index that stores the clustering key or row ID to the row data in its leaf nodes, depending on whether the table is a clustered table or a heap.
The ? character, when used in conjunction with the cast as keywords, is referred to as the optional occurrence indicator. It indicates that the empty sequence is allowed.
Object-relational mapping (O/RM)
O/RM is a technique for mapping data between relational databases and object-oriented programming languages.
The OWA is a logic formalism that states that the truth of a statement is independent of whether it is known to be true.
Parameterization
Parameterization is the act of using named or positional markers in place of constant values in a T-SQL query or statement. The actual values are passed to SQL Server independently of the actual query.
Predicate
AT-SQL predicate is an expression that evaluates to a SQL truth value. Predicates are used to control program flow and to limit the results of queries and the effect of statements.
An XQuery predicate is an expression enclosed in brackets ([]) that is used to filter a sequence. The predicate expressions are generally comparison expressions of some sort (equality, inequality, etc.).
Predicate truth value
In XQuery, a predicate truth value is a Boolean value derived from the result of an expression through a set of rules defined in the XQuery recommendation.
Primary expression
This is the basic primitive of the XQuery language. A primary expression can be a literal, a variable reference, a context item expression, a data type constructor, or a function call.
Query plan
A query plan is a sequence of logical and physical operators and data flows that the SQL query optimizer returns for use by the query processor to retrieve or modify data.
Recompilation
Recompilation is the process of compiling a new query plan for a given query, statement, or stored procedure (SP) when a plan already exists in the query plan cache. Recompilation can be triggered by SQL Server due to changes that have occurred since the prior query plan was generated for the statement, or it can be forced by user actions and T-SQL options.
Recursion
Recursion is a method of defining functions, CTEs, procedures, or triggers in such a way that they call themselves or cause themselves to be called multiple times.
Row constructor
A row constructor is a SQL Server 2012 feature that allows you to specify multiple rows in a single VALUES clause of the INSERT statement.
Searched CASE expression
A searched CASE expression allows you to specify one or more SQL predicates in WHEN clauses.
Sequence
XPath 2.0 and XQuery 1.0 define a sequence as an ordered collection of zero or more items. The term ordered is important here, as it differentiates a sequence from a set, which, as most T-SQL programmers know (or quickly come to realize), is unordered. XPath 1.0 defined its results in terms of node sets, which are unordered and cannot contain duplicates. XQuery changes this terminology to node sequences, which recognize the importance of node order in XML and can contain duplicates.
Server certificate
A server certificate is a certificate created in the master database for purposes of encrypting an entire database via transparent data encryption (TDE).
The SMK is an encryption key managed at the SQL Server service level. The SMK is used to encrypt all other keys in the SQL Server encryption key hierarchy.
Simple CASE expression
A simple CASE expression is defined with constants or value expressions in its WHEN clauses. The simple CASE evaluates to a series of simple equality expressions.
SOAP
SOAP, the Simple Object Access Protocol, is an XML-based protocol designed for exchanging structured information in distributed, decentralized environments.
Spatial data
Spatial data is used to represent objects and points on the earth.
Spatial index
A spatial index is a mechanism for increasing the efficiency of geographic calculations like the distance between points, or whether an object contains another point or object.
SQL Server Data Tools provides integrated environment for database and application development.
SQL injection
SQL injection is a technique that exploits security vulnerabilities in the application layer and middle tier, allowing users to execute arbitrary SQL statements on a server.
Step
A step in XQuery is composed of an axis, a node test, and zero or more predicates. Each step is a part of a path expression that generates a sequence of items and then filters the sequence.
Table type
This is an alias type that defines a table structure for use with table-valued parameters.
The SQL language supports 3VL with three truth values: true, false, and unknown.
Transparent data encryption (TDE)
TDE is a SQL Server 2012 feature that allows you to encrypt an entire database at once.
A UDA is a SQL CLR routine that applies a function or calculation to an entire set of values.
This is XML data that follows the W3C XML recommendation for well-formed data. It includes a single root element and properly nested elements, and is properly entitized.
Windowing functions
Windowing functions are functions that can partition and possibly order datasets before they are applied to the dataset partitions.
World Wide Web Consortium (W3C)
The W3C is a standards body with the stated mission of “developing interoperable technologies . . . to lead the Web to its full potential.”
XML
XML is the acronym for Extensible Markup Language, a restricted form of SGML (Standardized General Markup Language) designed to be easily served, received, and processed on the Web.
XML Schema
Part 2 of the XML Schema 1.1 standard defines XML Schema data types, which are the basic data types utilized by XQuery.
XPath
XPath, or XML Path Language, is an expression language designed to allow processing of values that conform to the XPath Data Model (XDM).
XQuery
XQuery, or XML Query Language, is an XML query language designed to retrieve and interpret data from diverse XML sources.
The XQuery 1.0 and XPath 2.0 Data Model is defined by the W3C at www.w3.org/TR/2006/PR-xpath-datamodel-20061121/. See XQuery.