Opening a SAS Data Set

Before you can access a SAS data set, you must first submit a command to open it. There are three ways to open a SAS data set:

• To simply read from an existing data set, submit a USE statement to open it for Read access. The general form of the USE statement is as follows:

  USE SAS-data-set <VAR operand> <WHERE(expression)> ;

  With Read access, you can use the FIND, INDEX, LIST, and READ statements with the data set.

• To read and write to an existing data set, use the EDIT statement. The general form of the EDIT statement is as follows:

  EDIT SAS-data-set <VAR operand> <WHERE(expression)> ;

  This statement enables you to use both the reading statements (LIST, READ, INDEX, and FIND) and the writing statements (REPLACE, APPEND, DELETE, and PURGE).

• To create a new data set, use the CREATE statement to open a new data set for both output and input. The general form of the CREATE statement is as follows:

  CREATE SAS-data-set <VAR operand> ;

  CREATE SAS-data-set FROM from-name ;

  < [COLNAME=column-name ROWNAME=row-name] > ; ;

  Use the APPEND statement to place the matrix data into the newly created data set. If you do not use the APPEND statement, the new data set has no observations.

If you want to list observations and create matrices from the data in the SAS data set named CLASS, you must first submit a statement to open the CLASS data set. Because CLASS already exists, specify the USE statement.