Glossary

calculated column

in a query, a column that does not exist in any of the tables that are being queried, but which is created as a result of a column expression.

Cartesian product

a type of join that matches each row from each joined table to each row from all other joined tables.

column

a vertical component of a table. Each column has a unique name, contains data of a specific type, and has particular attributes. A column is analogous to a variable in SAS terminology.

column alias

a temporary, alternate name for a column. Aliases are optionally specified in the SQL procedure's SELECT clause to name or rename columns. An alias is one word.

column expression

a set of operators and operands that, when evaluated, result in a single data value. The resulting data value can be either a character value or a numeric value.

composite index

an index that locates observations in a SAS data set by examining the values of two or more key variables.

condition

in the SQL procedure, the part of the WHERE clause that specifies which rows are to be retrieved.

cross join

a type of join that returns the product of joined tables. A cross join is functionally the same as a Cartesian product.

data set

See SAS data set.

data view

See SAS data view.

DISTINCT

a keyword that causes the SQL procedure to remove duplicate rows from the output.

equijoin

a kind of join in the SQL procedure. For example, when two tables are joined in an equijoin, the value of a column in the first table must equal the value of the column in the second table in the SQL expression.

format

See SAS format.

group

a set of rows or observations that have the same value or values for one or more common columns or variables.

in-line view

a query-expression that is nested in the SQL procedure's FROM clause. An in-line view produces a table internally that the outer query uses to select data. You save a programming step when you use an in-line view, because instead of creating a view and then referring to it in another query, you can specify the view in-line in the FROM clause. An in-line view can be referenced only in the query (or statement) in which it is defined.

index

a component of a SAS data set that enables SAS to access observations in the SAS data set quickly and efficiently. The purpose of SAS indexes is to optimize WHERE-clause processing and to facilitate BY-group processing.

inner join

a join between two tables that returns all of the rows in one table that have one or more matching rows in the other table.

integrity constraints

a set of data validation rules that you can specify in order to restrict the data values that can be stored for a variable in a SAS data file. Integrity constraints help you preserve the validity and consistency of your data.

join

an operation that combines data from two or more tables. A join is typically created by means of SQL (Structured Query Language) code or a user interface.

join criteria

the set of parameters that determine how tables are to be joined. Join criteria are usually specified in a WHERE expression or in an SQL ON clause.

missing value

a type of value for a variable that contains no data for a particular row or column. By default, SAS writes a missing numeric value as a single period and a missing character value as a blank space.

natural join

a type of join that returns selected rows from tables in which one or more columns in each table have the same name and the same data type and contain the same value.

outer join

a join between two tables that returns all of the rows in one table, as well as part or all of the rows in the other table. A left or right outer join returns all of the rows in one table (the table on the left or right side of the SQL statement, respectively), as well as the matching rows in the other table. A full outer join returns all of the rows in both of the tables.

pass-through facility

See SQL pass-through facility.

PROC SQL view

a SAS data set that is created by the SQL procedure. A PROC SQL view contains no data. Instead, it stores information that enables it to read data values from other files, which can include SAS data files, SAS/ACCESS views, DATA step views, or other PROC SQL views. The output of a PROC SQL view can be either a subset or a superset of one or more files.

query

a set of instructions that requests particular information from one or more data sources.

query expression

in PROC SQL, a SELECT statement that references at least one table and, when executed, creates a temporary table that exists only during the execution of the statement. You can combine the results of multiple table expressions with set operators to create a query expression.

SAS data file

a type of SAS data set that contains data values as well as descriptor information that is associated with the data. The descriptor information includes information such as the data types and lengths of the variables, as well as the name of the engine that was used to create the data.

SAS data set

a file whose contents are in one of the native SAS file formats. There are two types of SAS data sets: SAS data files and SAS data views. SAS data files contain data values in addition to descriptor information that is associated with the data. SAS data views contain only the descriptor information plus other information that is required for retrieving data values from other SAS data sets or from files whose contents are in other software vendors' file formats.

SAS data view

a type of SAS data set that retrieves data values from other files. A SAS data view contains only descriptor information such as the data types and lengths of the variables (columns) plus other information that is required for retrieving data values from other SAS data sets or from files that are stored in other software vendors' file formats. Short form: data view.

SAS format

a type of SAS language element that applies a pattern to or executes instructions for a data value to be displayed or written as output. Types of formats correspond to the data's type: numeric, character, date, time, or timestamp. The ability to create user-defined formats is also supported. Examples of SAS formats are BINARY and DATE. Short form: format.

simple index

an index that uses the values of only one variable to locate observations.

SQL

See Structured Query Language.

SQL pass-through facility

the technology that enables SQL query code to be passed to a particular DBMS for processing. Short form: pass-through facility.

Structured Query Language

a standardized, high-level query language that is used in relational database management systems to create and manipulate objects in a database management system. SAS implements SQL through the SQL procedure. Short form: SQL.

union join

a type of join that returns all rows with their respective values from each input table. Columns that do not exist in one table will have null (missing) values for those rows in the result table.

view

a definition of a virtual data set that is named and stored for later use. A view contains no data; it merely describes or defines data that is stored elsewhere.

WHERE clause

the keyword WHERE followed by one or more WHERE expressions.

WHERE expression

defines the criteria for selecting observations.