Oracle PL/SQL Tutorial/Collections/IS EMPTY
Версия от 16:45, 26 мая 2010; (обсуждение)
IS EMPTY Operator
You use the IS EMPTY operator to check if a nested table doesn"t contain elements. The following procedure, is_empty_example(), illustrates the use of IS EMPTY:
<source lang="sql">
SQL> SQL> CREATE OR REPLACE PROCEDURE is_empty_example AS
2 TYPE nestedTableType IS TABLE OF VARCHAR2(10); 3 myTable1 nestedTableType; 4 result BOOLEAN; 5 BEGIN 6 myTable1 := nestedTableType("F", "G", "S"); 7 result := myTable1 IS EMPTY; 8 IF result THEN 9 DBMS_OUTPUT.PUT_LINE("Nested table is empty"); 10 ELSE 11 DBMS_OUTPUT.PUT_LINE("Nested table contains elements"); 12 END IF; 13 END is_empty_example; 14 /
Procedure created. SQL> CALL is_empty_example(); Nested table contains elements Call completed. SQL> SQL></source>
IS EMPTY operator checks whether a VARRAY or NESTED TABLE collection variable is empty
<source lang="sql">
SQL> SQL> DECLARE
2 TYPE list IS TABLE OF INTEGER; 3 a LIST := list(); 4 BEGIN 5 IF a IS EMPTY THEN 6 dbms_output.put_line(""a" is empty."); 7 END IF; 8 END; 9 /
"a" is empty. PL/SQL procedure successfully completed. SQL></source>