显示游标的操作步骤：定义游标、打开游标、提取数据、关闭游标
1.定义游标
cursor cursor_name is select_statement;
2.打开游标
open cursor_name;
3.提取数据
语法一：fetch cursor_name into variable1,variable2...;
语法二：fetch cursor_name bulk collect into collect1,collect2,...[limit rows];
4.关闭游标：
close cursor_name;
游标属性：cursor_name%ISOPEN,cursor_name%FOUND
cursor_name%NOTFOUND,cursor_name%ROWCOUNT
Example 1:
declare
cursor emp_cursor is
select ename,sal from emp where dept=10;
v_ename emp.ename%TYPE;
v_sal emp.sal%TYPE;
begin
open emp_cursor;
loop
fetch emp_cursor into v_ename,v_sal;
exit when emp_cursor%NOTFOUND;
dbms_output.put_line(v_ename||': '||v_sal);
end loop;
close emp_cursor;
end;
Example 2(在显示游标中，使用fetch.. bulk collect into语句提取数据):
declare
cursor emp_cursor is
select ename from emp where deptno=10;
TYPE ename_table_type is TABLE OF VARCHAR2(10);
ename_table ename_table_type;
begin
open emp_cursor;
fetch emp_cursor bulk collect into ename_table;
for i in 1.. ename_table.count loop
dbms_output.put_line(ename_table(i));
end loop;
close emp_cursor;
end;
Example 3:(使用游标属性)
declare
cursor emp_cursor is
select ename from emp where deptno=10;
TYPE ename_table_type is TABLE OF VARCHAR2(10);
ename_table ename_table_type;
begin
if not emp_cursor%ISOPEN then
open emp_cursor;
end if;
fetch emp_cursor bulk collect into ename_table;
dbms_ouptput.put_line('提取的总计行数：'||emp_cursor%ROWCOUNT);
close emp_cursor;
end;
Example 4:(基于游标定义记录变量)
declare
cursor emp_cursor is select ename,sal from emp;
emp_record emp_cursor%ROWTYPE;
begin
open emp_cursor;
loop
fetch emp_cursor into emp_record;
exit when emp_cursor%NOTFOUND;
dbms_output.put_line('雇员名：'||emp_record.ename
||',雇员工资：'||emp_record.sal);
end loop;
close emp_cursor;
end;