2018-03-13《Oracle小脚本整理》

1.单表中名字去重

第一种思路型写法

 select *
        from gbase.gis_bridge a
       where bridge_id not in
             (select bridge_id
                from gbase.gis_bridge a
               where a.bridge_name in
                     (select bridge_name
                        from gbase.gis_bridge a 
                       group by bridge_name
                      having count(*) > 1)
                 and bridge_id not in (select min(bridge_id)
                                        from gbase.gis_bridge
                                       group by bridge_name
                                      having count(*) > 1));       

后来用了更为简单的方法

第二种简洁写法

select * from gbase.gis_bridge a
        where a.bridge_id in(
        select min(bridge_id) from gbase.gis_bridge a
        group by bridge_name)

2.查询并截取特殊字符的字段

截取出名称中从0开始到第一个扩号之前的数据

select substr(section_name,0,instr(section_name,'(',1)-1) from gbase.gis_cable_section

3.将竖向记录两两合并为横向记录

create table ywgl.wq_test(
action_id number primary key,
bill_id number,
starttime varchar2(255),
action varchar2(255)
)

insert into ywgl.wq_test values(1,1,'20170321','s');
insert into ywgl.wq_test values(2,1,'20170322','e');
insert into ywgl.wq_test values(3,1,'20170323','s');
insert into ywgl.wq_test values(4,1,'20170324','e');
insert into ywgl.wq_test values(5,1,'20170324','s');

select t1.starttime,t2.starttime from 
(select starttime,rownum rn from ywgl.wq_test where action='s') t1,
(select starttime,rownum rn from ywgl.wq_test where action='e') t2
where t1.rn=t2.rn(+)

4.Oracle分页查询语句

select *
  from (select s.*, rownum rn
          from (select * from ywgl.ywgl_action_record_gcph order by action_id) s
         where rownum <= 4)
 where rn >= 1

第二种

SELECT * FROM  
(  
SELECT A.*, ROWNUM RN  
FROM (select * from ywgl.ywgl_action_record_gcph order by action_id) A  
)  
WHERE RN BETWEEN 1 AND 4

5.Oracle获取不补0的月份

第一种：date型

-- end_date首先是date型
to_char(end_data, 'fmmm') billMonth

第二种: varchar型

-- 先将varchar转为date型 再获取
to_char(to_date(end_date, 'yyyy-mm-dd hh24:mi'), 'fmmm')

6.Date比较多种方式

第一种：通过varchar比较，适合数据量小的情况（因为大的情况用索引不方便）
where to_char(end_data,'yyyy-MM-dd')='2018-05-07'

第二种：直接date比较（end_date是date类型）
where end_date=date'2018-05-07'

7.字符串的截取

select bill_info_1,
 substr(bill_info_1,
              instr(bill_info_1, ':', 1, 2) + 1,
              instr(bill_info_1, '
', 1, 2) -
              (instr(bill_info_1, ':', 1, 2) + 1)) as "工程联系人",
       substr(bill_info_1,
              instr(bill_info_1, ':', 1, 3) + 1,
              instr(bill_info_1, '
', 1, 3) -
              (instr(bill_info_1, ':', 1, 3) + 1)) as "联系号码",
       substr(bill_info_1,
              instr(bill_info_1, ':', 1) + 1,
              instr(bill_info_1, '
', 1) -
              (instr(bill_info_1, ':', 1) + 1)) as "施工单位",
       substr(bill_info_1, instr(bill_info_1, ':', 1, 4) + 1) as "客保编号" from bill_info where kind_1_id=3

实现效果如下：

7.1字符串截取

8.字符串的截取函数

第七节可以发现如果有规律的数据，如果写一大串来截取，还不如写个函数来实现呢？实现的效果就是给定一个字符串，给定一个特殊字符，最后给定想要获取哪个位置的数据即可。（此函数是由同事毕兄所写，感谢毕兄帮我解决了这个问题）

create or replace function func_ywgl_substr_column (v_content in varchar2,v_identifier in varchar2,v_location in number) return varchar2 is

 v_result varchar2(4000);
 v_identifier_length number;
 v_instr number;
 v_instr_1 number;
 begin
  
  v_identifier_length :=length(v_identifier);
   v_instr :=instr(v_content,v_identifier,1,v_location);
   if v_location =1 then
     null;
     else
   v_instr_1 :=instr(v_content,v_identifier,1,v_location-1);
   end if;
   --if v_instr !=0 then
   if v_location=1 then
   v_result := substr(v_content ,1,instr(v_content,v_identifier,1,1)-1);
   elsif v_instr =0 and v_instr_1<>0 then
     v_result :=substr(v_content,instr(v_content,v_identifier,1,v_location-1)+v_identifier_length);
   else
   v_result := substr(v_content,v_identifier_length+instr(v_content,v_identifier,1,v_location-1),instr(v_content,v_identifier,1,v_location)-v_identifier_length-(instr(v_content,v_identifier,1,v_location-1)));
   end if;
   dbms_output.put_line(v_result);
   return(v_result);
 end;

下面就来验证下结果吧：

select bill_info_4,
       func_ywgl_substr_column(bill_info_4, '$', 1) a,
      func_ywgl_substr_column(bill_info_4, '$', 2) b,
      func_ywgl_substr_column(bill_info_4, '$', 3) c,
      func_ywgl_substr_column(bill_info_4, '$', 4) d,
       func_ywgl_substr_column(bill_info_4, '$', 5) e,
        func_ywgl_substr_column(bill_info_4, '$', 6) f,
      func_ywgl_substr_column(bill_info_4, '$', 7) g,
       func_ywgl_substr_column(bill_info_4, '$', 8) h
  from ywgl.ywgl_bill_info
 where ex_bill_id = 13508440
   and kind_1_id = 6 

运行结果如下：

图8.1 截取函数运行结果图