SQL 语句汇总(三)

转自: http://www.cnblogs.com/HondaHsu/archive/2007/07/03/803906.html
1.用游标取数据然后处理(Bulk collect 用法)

CREATE OR REPLACE TYPE A AS OBJECT (

id NUMBER(9),

name VARCHAR2 (20)

)

CREATE OR REPLACE TYPE atypelist
AS TABLE OF A;

/*定义type类型 A.

DECLARE

TYPE cur_type IS REF CURSOR;

TYPE tab_type IS TABLE OF A;

c_find_data cur_type;

v_tab tab_type;

BEGIN

OPEN c_find_data FOR 'SELECT * FROM A';

LOOP

FETCH c_find_data BULK COLLECT INTO v_tab LIMIT 10000; ---从游标中每取10000行存入bulk collect
的集合对象中

EXIT WHEN v_tab.count=0;

FOR i in 1..v_tab.count LOOP

--do you logic

END LOOP;

END LOOP;

CLOSE c_find_data;

END;

例子：

declare

type cur_type is ref cursor ;

type tb_type is table of a%rowtype;

cur_v cur_type;

tb_v tb_type;

begin

open cur_v for 'select * from a where rownum < 1000';

fetch cur_v bulk collect

into tb_v ;

forall i in 1 .. tb_v.count

insert into curv values tb_v(i);

close cur_v;

end;

2.将一个表的字段更新另一个表的字段

2.1 update m set m.money= (select n.money from n where n.id = m.id );

2.2 update m set m.money=n.money from n,m where m.id=n.id

3.求: 一个select 语句

现两个表:table1:

雇员ID 雇员姓名

empid empName

1 emp1

2 emp2

3 emp2

4 emp4

5 emp5

table2:

工程ID 角色1 角色2 角色3

gcid js1 js2 js3

1 1 2 3

2 2 3 4

3 3 4 5

其中:表2中的角色1/2/3对应表1中的雇员ID.

要求:写一select语句,将table2中的角色1\2\3显示为雇员姓名.

SQL:

SELECT gcid,

max(CASE WHEN js1 = empid THEN empname END) WHEN1,

max(CASE WHEN js2 = empid THEN empname END) WHEN2,

max(CASE WHEN js3 = empid THEN empname END) WHEN3

FROM mm,nn

GROUP BY gcid;

4.一维表的例子:

declare

i number;

type table1 is table of varchar2(9) index by binary_integer; */定义定义一维的type 类型

v_tab table1 ; */定义一维表的变量

cursor c is select salesman_name from sales_range where rownum<10;

str sales_range.salesman_name%type;

begin

open c;

for i in 1..9 loop

fetch c into str;

v_tab(i):=str;

insert into d values(v_tab(i));

end loop;

end;