Application of oracle pl/SQL programming SQL statements

Oracle pl/SQL programming the use of SQL statements select must have a return record, do not report an error saying that no data is found and must have an into select statement to return one and only one record cannot be written as where deptno = 10 because multiple records will be returned. Of course, the record mentioned here is not an absolute record, but a reference to the following usage for the variable to be assigned. The insert statement applies update in pl/SQL. it is also basically consistent that the variable SQL % rowcount is often used as a keyword to count the number of changed records. When the select statement is used, the rowcount value is the final number of records instead of the actual number. so generally, rowcount is only used to count the update, insert, and delete statements.