问题:

I have a table that stores RDF triples:

triples(triple_id, sub_id, pre_id, obj_id)

The method (I need to write) will receive an array of numbers which correspond to pre_id values. I want to select all sub_id values that have a corresponding pre_id for all the pre_ids in the array that is passed in.

E.g. if I had a single pre_id values passed in... lets call the value passed in preId, I would do:

select sub_id from triples where pre_id=preId;

However since I have mutliple pre_id values I want to keep iterating through the pre_id values and only keep the sub_id values corresponding to the "triples" records that have both.

E.g. image there are five records:

triples(1, 34,65,23) triples(2, 31,35,28) triples(3, 32,32,19) triples(4, 12,65,28) triples(5, 76,32,34)

If I pass in an array of pre_id values [65,32] then I want to select the first, third, fourth and fifth records.

What would I do for that?

回答1:

This might not work with every database, but the keyword in can do this:

select sub_id from triples where pre_id in (65, 32)

回答2:

You take in the incoming data as a single string, split it by delimiter, and put it into an @Table and use a JOIN, EXISTS or a sub query to get the rows back that you want.

Here is how to split a string into a @Table

T-SQL: Opposite to string concatenation - how to split string into multiple records

Fully working sample in SQL 2008

DROP FUNCTION dbo.Split go CREATE FUNCTION dbo.Split (@sep char(1), @s varchar(8000)) RETURNS table AS RETURN (     WITH Pieces(pn, start, stop) AS (       SELECT 1, 1, CHARINDEX(@sep, @s)       UNION ALL       SELECT pn + 1, stop + 1, CHARINDEX(@sep, @s, stop + 1)       FROM Pieces       WHERE stop > 0     )     SELECT pn,       SUBSTRING(@s, start, CASE WHEN stop > 0 THEN stop-start ELSE 512 END) AS s     FROM Pieces   ) GO Declare @Triples Table   (     triple_id Int,      sub_id VarChar (10),       pre_id VarChar (10),       obj_id VarChar (10) )  INSERT INTO @Triples  VALUES (1, 34,65,23), (2, 31,35,28), (3, 32,32,19), (4, 12,65,28), (5, 76,32,34)  SELECT *  FROM @Triples Triples     INNER JOIN dbo.split (',', '65,32') as InputValues         ON Triples.pre_id = InputValues.S

回答3:

You can use sub query like this.

select sub_id from triples where pre_id IN (Select pre_id from triples where pre_id <= 65 AND pre_id => 32 )

回答4:

One of Way you could do it is using Table Value Function whic exists in MSSQL (sory but I do not know for others)

   CREATE FUNCTION [dbo].[fn_ado_test] (@ado nvarchar(4000), @Delim char(1)= ',')    RETURNS @VALUES TABLE (ado nvarchar(4000),id int)AS    BEGIN    DECLARE @chrind INT     DECLARE @id int    DECLARE @Piece nvarchar(4000)     SELECT @chrind = 1,@id=0    WHILE @chrind > 0       BEGIN          SELECT @chrind = CHARINDEX(@Delim,@ado),@id=@id+1          IF @chrind > 0             SELECT @Piece = LEFT(@ado,@chrind - 1)          ELSE             SELECT @Piece = @ado           INSERT @VALUES(ado,id) VALUES(@Piece,@id)          SELECT @ado = RIGHT(@ado,LEN(@ado) - @chrind)          IF LEN(@ado) = 0 BREAK       END    RETURN END

After that you use statement like this

/*--For First argument --*/     select ado from [dbo].[fn_ado_test]('1,2,3',',') as parametar     where parametar.id=1  /*-- Second --*/ select ado from [dbo].[fn_ado_test]('1,2,3',',') as parametar         where parametar.id=2

回答5:

SELECT sub_id FROM triples WHERE pre_id IN (65, 32)

seems to work for me.

NB: Using MySQL.

转载请标明出处:How to select a subset of results from a select statement

文章来源: How to select a subset of results from a select statement

标签

select

sub