oracle游标的实例,oracle游标实例

–游标

—-游标：当在PL/SQL块中执行查询语句和数据操作语句时，oracle会为其分配上下文区，游标是指向上下文区的指针。

—-显示游标：显示游标在PL/SQL块的声明部分声明，在执行部分或异常处理部分打开游标，提取数据，关闭游标。

—-使用游标不得步骤：

a.定义游标

declare cursor cursor_name(游标名) is select_statement(select语句);

b.打开游标

open cursor_name

c.提取数据

fetch cursor_name into 参数1，参数2……

或

fetch cursor_name bulk collection into collect1,collect2,……

d.关闭游标

close cursor_name;

–每次提取一行数据

declare

cursor emp_cursor

is

select ename,sal from scott.emp where deptno=20;

v_ename scott.emp.ename%type;

v_sal scott.emp.sal%type;

begin

–打开游标

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;

–关闭游标

close emp_cursor;

end;

—每次提取多行数据

declare

cursor emp_cur

is

select ename,sal from scott.emp where deptno=20;

type v_names is table of scott.emp.ename%type

index by binary_integer;

type v_sals is table of scott.emp.sal%type

index by binary_integer;

names v_names;

sals v_sals;

begin

open emp_cur;

fetch emp_cur bulk collect into names,sals;

for i in 1..names.count loop

dbms_output.put_line(sals(i));

end loop;

close emp_cur;

end;

—-参数游标

declare

cursor emp_cursor(cno number)

is

select ename,sal from scott.emp where deptno=cno;

v_ename scott.emp.ename%type;

v_sal scott.emp.sal%type;

begin

if not emp_cursor%isopen then

open emp_cursor(10);—传入参数

end if;

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;

—-使用游标更新或删除数据

declare

cursor emp_cursor

is

select ename,sal from scott.emp for update of sal;

v_ename scott.emp.ename%type;

v_oldsal scott.emp.sal%type;

begin

open emp_cursor;

loop

–从游标中提取数据

fetch emp_cursor into v_ename,v_oldsal;

exit when emp_cursor%notfound;

–判断

if v_oldsal<2500 then

update scott.emp set sal=sal+150 where current of emp_cursor;

end if;

end loop;

close emp_cursor;

end;

–查询薪水

select * from scott.emp;

–游标的for循环

declare

cursor emp_cursor

is

select ename from scott.emp where deptno=20;

begin

for emp_record in emp_cursor loop

dbms_output.put_line(‘第’||emp_cursor%rowcount||’个员工’||emp_record.ename);

end loop;

end;

–显示游标属性

%isopen 判断游标是否打开，如果游标已经打开，则返回true,否则返回false;

%found  检查是否从结果集中提取了数据。如果提取返回true,否则返回false;

%not found   该属性与%found相反；

rowcount   返回到当前行数止已经提取到的实际行数。