Oracle查询选择

Question

我有一个表格说变量，其中一列存在名称“名称”。现场有值喜欢 -

abc_R01 
    abc_R02 
    abc_R03 
    pqrs_R01 
    pqrs_R02 
    xyz_R01 
    xyz_R02 
    xyz_R03 
    xyz_R04 

现在我的选择标准是一样，我有选择的每一个最新的变量名，即我可以发射单/复杂的查询，以获得结果喜欢 -

abc_R03 
    pqrs_R02 
    xyz_R04 

或者我需要通过我的代码来处理它，这里_Rxx表示修改我的变量。 请帮帮我。

Answer 1

请尝试：

select 
    Col 
from 
(
    select 
    Col, 
    row_number() over (partition BY substr(Col, 0, instr(Col, '_')) order by regexp_substr(col, '\d+$') DESC) rn 
    from YourTable 
)x where rn=1; 

检查下面的查询在10个G

select 
    Col 
from 
(
    select 
    Col, 
    row_number() over (partition BY substr(Col, 0, instr(Col, '_')) order by substr(col, instr(col, 'R')+1) DESC) rn 
    from YourTable 
)x where rn=1; 

SQL Fiddle Demo

Answer 2

select name 
from 
(
select 
    substr("name",0,length("name")-1) as n1,max("name") as name 
from Table1 
    group by substr("name",0,length("name")-1) 
)t 

SQL Fiddle

Answer 3

这也将帮助你，

WITH t(NAME) AS 
(
SELECT 'abc_R01' FROM dual 
UNION 
SELECT 'abc_R02' FROM dual 
UNION 
SELECT 'abc_R03' FROM dual 
UNION 
SELECT 'pqrs_R01' FROM dual 
UNION 
SELECT 'pqrs_R02' FROM dual 
UNION 
SELECT 'xyz_R01' FROM dual 
UNION 
SELECT 'xyz_R02' FROM dual 
UNION 
SELECT 'xyz_R03' FROM dual 
UNION 
SELECT 'xyz_R04' FROM dual 
) 
SELECT NAME 
FROM (
    SELECT substr(NAME, 0, instr(NAME, 'R')), 
      MAX(NAME) NAME 
    FROM t 
    GROUP BY substr(NAME, 0, instr(NAME, 'R')) 
    );