SAS/ACCESS 9.2 for Relational Databases: Reference, Fourth Edition

How SAS/ACCESS Works 4 How the DBLOAD Procedure Works 65because the table might have been updated by another user between procedureexecutions.)proc print data=vlib.allemp;run;proc gchart data=vlib.allemp;vbar jobcode;run;Updating DataYou use a view descriptor, DATA step, or procedure to update DBMS data in asimilar way as when you read in data. Any of these steps might also occur:3 Using the connection information that is contained in the specified accessdescriptor, the SAS/ACCESS interface calls the DBMS to connect to the database.3 When rows are added to a table, SAS constructs an SQL INSERT statement andpasses it to the DBMS. When you reference a view descriptor, use the ADDcommand in FSEDIT and FSVIEW, the APPEND procedure, or an INSERTstatement in PROC SQL to add data to a DBMS table. (You can also use theEXECUTE statement for the SQL pass-through facility to add, delete, or modifyDBMS data directly. Literal values must be used when inserting data with theSQL pass-through facility.)3 When rows are deleted from a DBMS table, SAS constructs an SQL DELETEstatement and passes it to the DBMS. When you reference a view descriptor, youcan use the DELETE command in FSEDIT and FSVIEW or a DELETE statementin PROC SQL to delete rows from a DBMS table.3 When data in the rows is modified, SAS constructs an SQL UPDATE statementand passes it to the DBMS. When you reference a view descriptor, you can useFSEDIT, the MODIFY command in FSVIEW, or an INSERT statement in PROCSQL to update data in a DBMS table. You can also reference a view descriptor inthe DATA step’s UPDATE, MODIFY, and REPLACE statements.3 SAS closes the connection with the DBMS.How the DBLOAD Procedure WorksWhen you use the DBLOAD procedure to create a DBMS table, the procedure issuesdynamic SQL statements to create the table and insert data from a SAS data file,DATA step view, PROC SQL view, or view descriptor into the table.The SAS/ACCESS interface view engine completes these steps:1 When you supply the connection information to PROC DBLOAD, theSAS/ACCESS interface calls the DBMS to connect to the database.2 SAS uses the information that is provided by the DBLOAD procedure to construct aSELECT * FROM table-name statement, and passes the information to the DBMSto determine whether the table already exists. PROC DBLOAD continues only if atable with that name does not exist, unless you use the DBLOAD APPEND option.3 SAS uses the information that is provided by the DBLOAD procedure to constructan SQL CREATE TABLE statement and passes it to the DBMS.4 SAS constructs an SQL INSERT statement for the current observation and passesit to the DBMS. New INSERT statements are constructed and then executedrepeatedly until all observations from the input SAS data set are passed to the