Glossary
- alias
a temporary, alternate name assigned to a table for use in a join query.
- base table
a primary table.
- CALCULATED column
a column that is used in the same SELECT statement in which the calculation occurs.
- Cartesian product
a type of join that yields all the possible combinations of rows and columns.
- case expression
an expression that specifies relations among columns and values in conditional logic. Similar to IF-THEN logic.
- clause
part of an SQL statement, beginning with a keyword such as SELECT and generally containing an argument.
- column
a field or variable in a table. Each column has a unique name, contains data of a specific type, and has certain attributes.
- column-definition
refers to a column name and column attributes including type, length, informat, format, and label information.
- composite index
a separate SAS file (stored in the same SAS library the data resides in) consisting of directions that permit access to rows of data based on two or more columns within a table.
- concatenation operator
an operator that allows two or more character strings to be concatenated together forming a single string.
- correlated subquery
a subquery that evaluates multiple times, once for each row of data accessed by the main query.
- Data Definition Language (DDL)
statements that define (redefine) the definition of one or more existing tables.
- database design
the process of identifying end-user requirements and defining the structure of data values on a physical level.
- DISTINCT keyword
a keyword that selects duplicate values in a column only one time and causes the SQL procedure to remove duplicate rows from the output.
- equijoin
a join in which all the columns in two or more tables being joined are included in the results based on the comparison of columns being equal.
- index
a data structure that permits a row of data in a table to be located without having to read the entire table.
- intersect
an output table consisting of all the unique rows from the intersection of two query expressions.
- join
the combination of data from two or more tables to produce a single result table.
- key
identification of a row of data by the columns in an index.
- missing value
a term that describes the contents of a variable that contains no data for a particular row or observation. A missing value is equivalent to an SQL null value.
- nesting
views that are dependent on other views.
- normalization
the process of ensuring that a database does not contain redundant information in two or more of its tables.
- null value
a special value that indicates the absence of information. Analogous to missing values.
- ODS
the Output Delivery System provides formatting engines to automatically convert monospace output into more readable, proportionally spaced output.
- operator
any of several symbols that request a comparison, a logical operation, or an arithmetic calculation.
- outer join
an asymmetric join where rows are selected unproportionally from its parts. There are three kinds: left, right, and full. See also join.
- pattern matching
technique used to find patterns in data.
- performance tuning
process of improving the efficiency of a query, join, insert, update, or delete operation in a way to reduce the unnecessary expenditure of computer resources.
- phonetic matching
the sounds-like operator searches and selects character data that sound alike or have spelling variations.
- predicate
an object used to perform direct comparisons between two conditions or expressions.
- query
a set of instructions that requests particular information from one or more data sources.
- row
the horizontal component of a table.
- scalar expression
a quantity represented by a single number or value.
- self-join
a single table that is joined with itself.
- set operator
an operator that combines or merges separate queries together.
- simple index
a separate SAS file (stored in the same SAS library the data resides in) consisting of directions that permit access to rows of data based on a single column within a table.
- sounds-like operator
see phonetic matching.
- subquery
a query that is embedded in a WHERE clause of the main query.
- symmetric join
an equal selection from two parts.
- union
an output table consisting of all the unique rows from the combination of query expressions.
- updatable view
a view that is able to update a physical table.
- view
a virtual table (non-existent) that contains a set of instructions on how to obtain data from base tables.
- virtual table
a virtual table does not contain any data but is a query consisting of a set of instructions.