SAS Data Set Options

INDEX= Data Set Option

Defines an index for a new output SAS data set.

Valid in:	DATA step and PROC steps
Category:	Data Set Control
Restriction:	Use with output data sets only.

Syntax
Syntax Description
Examples
	Example 1: Defining a Simple Index
	Example 2: Defining a Composite Index
	Example 3: Defining a Simple and a Composite Index
	Example 4: Defining a Simple Index with the UNIQUE Option
	Example 5: Defining a Simple Index with the NOMISS Option
	Example 6: Defining Multiple Indexes Using the UNIQUE and NOMISS Options
See Also

Syntax

INDEX=(index-specification-1 ...<index-specification-n>)

Syntax Description

index-specification

names and describes a simple or a composite index to be built. Index-specification has this form:

index= (variable(s) </UNIQUE> </NOMISS>)

index: is the name of a variable that forms the index or the name you choose for a composite index.
variable or variables: is a list of variables to use in making a composite index.
UNIQUE: specifies that the values of the key variables must be unique. If you specify UNIQUE for a new data set and multiple observations have the same values for the index variables, the index is not created. A slash (/) must precede the UNIQUE option.
NOMISS: excludes all observations with missing values from the index. Observations with missing values are still read from the data set but not through the index. A slash (/) must precede the NOMISS option.

Examples

Example 1: Defining a Simple Index

The following INDEX= data set option defines a simple index for the SSN variable:

data new(index=(ssn));

Example 2: Defining a Composite Index

The following INDEX= data set option defines a composite index named CITYST that uses the CITY and STATE variables:

data new(index=(cityst=(city state)));

Example 3: Defining a Simple and a Composite Index

The following INDEX= data set option defines a simple index for SSN and a composite index for CITY and STATE:

data new(index=(ssn cityst=(city state)));

Example 4: Defining a Simple Index with the UNIQUE Option

The following INDEX= data set option defines a simple index for the SSN variable with unique values:

data new(index=(ssn /unique));

Example 5: Defining a Simple Index with the NOMISS Option

The following INDEX= data set option defines a simple index for the SSN variable, excluding all observations with missing values from the index:

data new(index=(ssn /nomiss));

Example 6: Defining Multiple Indexes Using the UNIQUE and NOMISS Options

The following INDEX= data set option defines a simple index for the SSN variable and a composite index for CITY and STATE. Each variable must have a UNIQUE and NOMISS option:

data new(index=(ssn /unique/nomiss cityst=(city state)/unique/nomiss));

	INDEX CREATE statement in "The DATASETS Procedure" in Base SAS Procedures Guide
	CREATE INDEX statement in "The SQL Procedure" in Base SAS Procedures Guide
	Understanding SAS Indexes in in the "SAS Data Files" section of SAS Language Reference: Concepts