I need to write a write a SQL query that selects values from a table based on several tuples of selection criteria. It could be done using a where clause like this :
where (a = 1 and b='a') or (a=5 and b='s')
Is the best way to select:
select a, pk from x where a in (1,5)
select b, pk from x where b in ('a','s')
and join the result of the two queries using the primary key?
do you mean something(a self join) like this:
select x.a, x.pk
from x
join x x2 on x.pk=x2.pk
where x.a in (1,5)
and x2.b in ('a','s')
?
You can use join on table expression from VALUES. You can add in VALUES as much rows as you want. It will work on MSSQL:
DECLARE #x TABLE ( a INT, b CHAR(1) )
INSERT INTO #x
VALUES ( 1, 'a' ),
( 1, 'b' ),
( 1, 'c' ),
( 2, 'd' ),
( 2, 'e' ),
( 5, 'f' ),
( 5, 's' )
SELECT x.*
FROM #x x
JOIN (
VALUES ( 1, 'a'),
( 5, 's')
) AS v( a, b ) ON x.a = v.a AND x.b = v.b
Output:
a b
1 a
5 s
Based on my understanding you want write a SQL that uses a combination of two filters. Here is a simple solution that will work in any database.
Create a new column say "COLUMN_NEW" in the same table or build a temp table or a view with a new column (plus existing columns from original table).
Insert concatenated values of column a and column b in "COLUMN_NEW". Based on the example mentioned by you values in "COLUMN_NEW" will be "1a" and "5s"
Now you may have a different syntax for concat in different databases. Example concat(a,b) in SQL server.
SQL to select records from the table will be select * from table where COLUMN_NEW in ("1a",5s");
Related
So i have a union query like:
select count(id)
from table 1
where membernumber = 'x'
and castnumber = 'y'
union
select count(id)
from table 1
where membernumber = 'x'
and castnumber = 'y'
union
etc...
There will be over 200 unions coming from a list 2x 200 table with values for x and y in each row. So each union query has to get the value of x and y from the corresponding row (not in any particular order).
How can i achieve that ?
Thanks
Try this:
DECLARE GLOBAL TEMPORARY TABLE
SESSION.PARAMETERS
(
MEMBERNUMBER INT
, CASTNUMBER INT
) DEFINITION ONLY WITH REPLACE
ON COMMIT PRESERVE ROWS NOT LOGGED;
-- Insert all the the constants in your application with
INSERT INTO SESSION.PARAMETERS
(MEMBERNUMBER, CASTNUMBER)
VALUES (?, ?);
-- I don't know the meaning of the result you want to get
-- but it's equivalent
select distinct count(t.id)
from table1 t
join session.parameters p
on p.membernumber = t.membernumber
and p.castnumber = t.castnumber
group by t.membernumber, t.castnumber;
I'm trying to group by a primary column and a secondary column. I want to ignore NULL in the secondary column unless it's the only value.
CREATE TABLE #tempx1 ( Id INT, [Foo] VARCHAR(10), OtherKeyId INT );
INSERT INTO #tempx1 ([Id],[Foo],[OtherKeyId]) VALUES
(1, 'A', NULL),
(2, 'B', NULL),
(3, 'B', 1),
(4, 'C', NULL),
(5, 'C', 1),
(6, 'C', 2);
I'm trying to get output like
Foo OtherKeyId
A NULL
B 1
C 1
C 2
This question is similar, but takes the MAX of the column I want, so it ignores other non-NULL values and won't work.
I tried to work out something based on this question, but I don't quite understand what that query does and can't get my output to work
-- Doesn't include Foo='A', creates duplicates for 'B' and 'C'
WITH cte AS (
SELECT *,
ROW_NUMBER() OVER (PARTITION BY [Foo] ORDER BY [OtherKeyId]) rn1
FROM #tempx1
)
SELECT c1.[Foo], c1.[OtherKeyId], c1.rn1
FROM cte c1
INNER JOIN cte c2 ON c2.[OtherKeyId] = c1.[OtherKeyId] AND c2.rn1 = c1.rn1
This is for a modern SQL Server: Microsoft SQL Server 2019
You can use a GROUP BY expression with HAVING clause like below one
SELECT [Foo],[OtherKeyId]
FROM #tempx1 t
GROUP BY [Foo],[OtherKeyId]
HAVING SUM(CASE WHEN [OtherKeyId] IS NULL THEN 0 END) IS NULL
OR ( SELECT COUNT(*) FROM #tempx1 WHERE [Foo] = t.[Foo] ) = 1
Demo
Hmmm . . . I think you want filtering:
select t.*
from #tempx1 t
where t.otherkeyid is not null or
not exists (select 1
from #tempx1 t2
where t2.foo = t.foo and t2.otherkeyid is not null
);
My actual problem is a bit more complicated than presented here, I ended up using the idea from Barbaros Özhan solution to count the number of items. This ends up with two inner queries on the data set with two different GROUP BY. I'm able to get the results I need on my real dataset using a query like the following:
SELECT
a.[Foo],
b.[OtherKeyId]
FROM (
SELECT
[Foo],
COUNT([OtherKeyId]) [C]
FROM #tempx1 t
GROUP BY [Foo]
) a
JOIN (
SELECT
[Foo],
[OtherKeyId]
FROM #tempx1 t
GROUP BY [Foo], [OtherKeyId]
) b ON b.[Foo] = a.[Foo]
WHERE
(b.[OtherKeyId] IS NULL AND a.[C] = 0)
OR (b.[OtherKeyId] IS NOT NULL AND a.[C] > 0)
You have parameters x,y,z stored as key values.
You want to execute an expression z=x+y on those parameters. Expression is stored in another table.
You want to generate an SQL query as simply as possible from the expression.
How can you view those parameter values as a single row with columns (x,y,z) to enable execution of the expression ?
SELECT *
INTO #key_values
FROM
(
SELECT 'x' AS mykey, 2 AS myvalue
UNION ALL
SELECT 'y', 5
UNION ALL
SELECT 'z', 0
) a;
This screams for a PIVOT operator:
;WITH Inputs AS
(
SELECT 'x' AS mykey, 2 AS myvalue
UNION ALL
SELECT 'y', 5
UNION ALL
SELECT 'z', 0
)
SELECT
U.x,
U.y,
U.z,
Result = U.x + U.y
FROM
Inputs AS I
PIVOT (
MAX(I.myvalue) FOR I.mykey IN (x, y, z)
) AS U
Results:
x y z Result
2 5 0 7
You can build any expression you want with the pivoted columns in the SELECT.
If you want to update the z record, you will have to join back to the underlying table since after applying the PIVOT you lose access to original table.
IF OBJECT_ID('tempdb..#Input') IS NOT NULL
DROP TABLE #Input
CREATE TABLE #Input (
mykey VARCHAR(10),
myvalue INT)
INSERT INTO #Input (
mykey,
myvalue)
VALUES
('x', 2),
('y', 5),
('z', 0)
UPDATE I SET
myvalue = R.Result
FROM
#Input AS I
CROSS APPLY (
SELECT
Result = x + y
FROM
#Input AS I
PIVOT (MAX(I.myvalue) FOR I.mykey IN (x, y, z)) AS U
) AS R
WHERE
I.mykey = 'z'
Turn the 3 rows into a single 3 column row using a common table expression and update it to run the expression. So the proposed solution is an updatable cte.
WITH myvalues(x,y,z) AS (
SELECT x.myvalue, y.myvalue, z.myvalue
FROM #key_values AS x
JOIN #key_values AS y ON y.mykey='y' AND x.mykey='x'
JOIN #key_values AS z ON z.mykey='z'
)
UPDATE myvalues SET z=x+y;
SELECT myvalue FROM #key_values WHERE mykey='z';
I would like my SQL query to return a row even if there is no row matching in my IN clause.
For exemple this query:
SELECT id, foo
FROM table
WHERE id IN (0, 1, 2, 3)
would return:
id|foo
0|bar
1|bar
2|bar
3|null
But instead I have (because no row with id 3):
id|foo
0|bar
1|bar
2|bar
I have been able to find this trick:
SELECT tmpTable.id, table.bar
FROM (
SELECT 0 as id
UNION SELECT 1
UNION SELECT 2
UNION SELECT 3
) tmpTable
LEFT JOIN
(
SELECT table.foo, table.id
FROM table
WHERE table.id IN (0, 1, 2, 3)
) table
on table.id = tmpTable.id
Is there a better way?
Bonus: How to make it work with myBatis's list variable?
overslacked is right. Most SQL developers use an auxiliary table that stores integers (and one that stores dates). This is outlined in an entire chapter of Joe Celko's "SQL for Smarties".
Example:
CREATE TABLE numeri ( numero INTEGER PRIMARY KEY )
DECLARE #x INTEGER
SET #x = 0
WHILE #x < 1000
BEGIN
INSERT INTO numeri ( numero ) VALUES ( #x )
SET #x = #x + 1
END
SELECT
numero AS id,
foo
FROM
numeri
LEFT OUTER JOIN my_table
ON my_table.id = numero
WHERE
numero BETWEEN 0 AND 3
Main Goal of Programming minimal code high performance no need this things just remove id 3 from in clause
What about just saying:
SELECT id, foo
FROM table
WHERE id >= 0 AND <= 3
Suppose I have a list of values, such as 1, 2, 3, 4, 5 and a table where some of those values exist in some column. Here is an example:
id name
1 Alice
3 Cindy
5 Elmore
6 Felix
I want to create a SELECT statement that will include all of the values from my list as well as the information from those rows that match the values, i.e., perform a LEFT OUTER JOIN between my list and the table, so the result would be like follows:
id name
1 Alice
2 (null)
3 Cindy
4 (null)
5 Elmore
How do I do that without creating a temp table or using multiple UNION operators?
If in Microsoft SQL Server 2008 or later, then you can use Table Value Constructor
Select v.valueId, m.name
From (values (1), (2), (3), (4), (5)) v(valueId)
left Join otherTable m
on m.id = v.valueId
Postgres also has this construction VALUES Lists:
SELECT * FROM (VALUES (1, 'one'), (2, 'two'), (3, 'three')) AS t (num,letter)
Also note the possible Common Table Expression syntax which can be handy to make joins:
WITH my_values(num, str) AS (
VALUES (1, 'one'), (2, 'two'), (3, 'three')
)
SELECT num, txt FROM my_values
With Oracle it's possible, though heavier From ASK TOM:
with id_list as (
select 10 id from dual union all
select 20 id from dual union all
select 25 id from dual union all
select 70 id from dual union all
select 90 id from dual
)
select * from id_list;
the following solution for oracle is adopted from this source. the basic idea is to exploit oracle's hierarchical queries. you have to specify a maximum length of the list (100 in the sample query below).
select d.lstid
, t.name
from (
select substr(
csv
, instr(csv,',',1,lev) + 1
, instr(csv,',',1,lev+1 )-instr(csv,',',1,lev)-1
) lstid
from (select ','||'1,2,3,4,5'||',' csv from dual)
, (select level lev from dual connect by level <= 100)
where lev <= length(csv)-length(replace(csv,','))-1
) d
left join test t on ( d.lstid = t.id )
;
check out this sql fiddle to see it work.
Bit late on this, but for Oracle you could do something like this to get a table of values:
SELECT rownum + 5 /*start*/ - 1 as myval
FROM dual
CONNECT BY LEVEL <= 100 /*end*/ - 5 /*start*/ + 1
... And then join that to your table:
SELECT *
FROM
(SELECT rownum + 1 /*start*/ - 1 myval
FROM dual
CONNECT BY LEVEL <= 5 /*end*/ - 1 /*start*/ + 1) mypseudotable
left outer join myothertable
on mypseudotable.myval = myothertable.correspondingval
Assuming myTable is the name of your table, following code should work.
;with x as
(
select top (select max(id) from [myTable]) number from [master]..spt_values
),
y as
(select row_number() over (order by x.number) as id
from x)
select y.id, t.name
from y left join myTable as t
on y.id = t.id;
Caution: This is SQL Server implementation.
fiddle
For getting sequential numbers as required for part of output (This method eliminates values to type for n numbers):
declare #site as int
set #site = 1
while #site<=200
begin
insert into ##table
values (#site)
set #site=#site+1
end
Final output[post above step]:
select * from ##table
select v.id,m.name from ##table as v
left outer join [source_table] m
on m.id=v.id
Suppose your table that has values 1,2,3,4,5 is named list_of_values, and suppose the table that contain some values but has the name column as some_values, you can do:
SELECT B.id,A.name
FROM [list_of_values] AS B
LEFT JOIN [some_values] AS A
ON B.ID = A.ID