从MS Sql中的表中选择值的不同集合

Question

I have table in my db which is in MSSQL having following structure

DayID      Sequence           Cities       Title     Hotels   
----------------------------------------------------------------
1                 1             Manali       Day1      Hotel A      
2                 2             Manali       Day2      Hotel B     
3                 2             Delhi        Day3      Hotel C    
4                 3             Delhi        Day4      Hotel D     
5                 3             Manali       Day5      Hotel E    
6                 4             Manali       Day6      Hotel F 

Now I need The result as following

Cities
------   
Manali    
Delhi   
Manali.

I have used group by Cities but it is giving only two cities

Manali
Delhi 

But I need following output.

Manali    
Delhi   
Manali

Please Suggest.

Thanks in Advance.

Answer 1

Try this:

SELECT Cities
FROM (
   SELECT Cities, DayID,
          ROW_NUMBER() OVER (ORDER BY DayID) -
          ROW_NUMBER() OVER (PARTITION BY Cities ORDER BY DayID) AS grp
   FROM mytable) AS t
GROUP BY Cities, grp
ORDER BY MIN(DayID)

Calculated field grp identifies islands of consecutive records having the same Cities value. Using this field in a GROUP BY clause, we can extract the required sequence of Cities values.

Note: The above query works in SQL Server.

Answer 2

根据要求，您可以按以下方式分组：从表中按城市选择城市

Answer 3

First make sure the table is sorted so we can use the 'by' option in the data step:

 proc sort data=tablename;
 by sequence cities;
 run;

In the data step use the 'by' clause to select the first row of each group and output. Only 'keep' cities as requested by user

 data desired;
 keep cities;
 set tablename;
 by sequence cities;
 if first.cities then output;
 run;