How can I make a sql query like the following:
(SELECT `name` FROM table1)
UNION
(SELECT `name` FROM table2)
return each other. Ie. name1 from table1, name1 from table2, name2 from table1, name2 from table2 and so on?
Edit:
Table1
name
Hello
world
Table2
name
guten
tag
The output wanted:
Hello
guten
world
tag
and this should also be possible if adding more unions, so that it takes from the first union, then the second, third, forth and so on.
You could number rows with variables, using 2,4,6,... for the first part of the union and 3,5,7,... for the second:
select #rownum1 := #rownum1+2 as rownum, name
from (select #rownum1:=0) r, table1
union all
select #rownum2 := #rownum2+2 as rownum, name
from (select #rownum2:=1) r, table2
order by rownum;
The select in the from clause (select #rownum2:=1) r is only used to initialize the variable.
Does this work?
set #i = 0;
set #j = 1;
select #i:=#i+2 as rownumber,
name
from table1
union
select #j:=#j+2 as rownumber,
name
from table2
order by rownumber
I read your question as wanting to alternate one row from table1, one from table2 and so on in your results set.
Edit in light of your edit:
Change the "2"s to the number of tables, and add as many variables as you have tables, with consecutive start values in the "set" statements. This will extend in the way you want.
In a similar vein to David M, you can do:
(SELECT #rownum:=#rownum+1 as rownum,`name` FROM table1, (SELECT #rownum:=0) r)
UNION
(SELECT #rownum:=#rownum+1 as rownum,`name` FROM table2, (SELECT #rownum:=0) r)
order by rownum
Related
I want to make a selection from one of many tables. This selection depends on some condition. How can I make it?
I suppose it should be some like this (but it doesn't work):
CASE x
WHEN x=1 THEN
select Id,Name from table1
WHEN x=2 THEN
select Id,Name from table2
WHEN x=3 THEN
select Id,Name from table3
END CASE;
Inefficient solution the queries all 3 tables, but immitates a switch statement in code (assuming the retrieved columns are equivalent)
declare #inputValue int = 1
SELECT * FROM (
SELECT 1 [key], Id from table1
UNION ALL
SELECT 2, Id from table2
UNION ALL
SELECT 3, Id from table3
) x
where x.[key] = #inputValue
One way to do it:
SELECT id, name
FROM table1
WHERE x = 1
UNION ALL
SELECT id, name
FROM table2
WHERE x = 2
UNION ALL
SELECT id, name
FROM table3
WHERE x = 3
Only one table's data will be returned (if x is any of those values).
Using SQL Server, I have two tables that I want to merge. Table2 has a tbID column that has NULL values. I would like for NULL values to be automatically updated, beginning with the next value of the tbID column, from Table1 when the tables are merged.
I am entering something like this..
SELECT
A.tbID,
A.etID,
A.cNumber,
A.cName
FROM
Table1 AS A
UNION ALL
SELECT
B.tbID,
B.etID,
B.cNumber,
B.cName
FROM
Table2 AS B
My results has a NULL value (instead of an automatically inserted number), in the records from Table2.
If by "merge" you want all the records to end up in table1 - just leave the id column out of the insert:
INSERT INTO table1 (etID, cNumber, cName)
SELECT etID, cNumber, cName
FROM table2
If you just want to select and see incremented ids for the data coming from table2, here is one way:
SELECT A.tbID,
A.etID,
A.cNumber,
A.cName
FROM Table1 AS A
UNION ALL
SELECT (SELECT MAX(tbID) FROM Table1) +
ROW_NUMBER() OVER (ORDER BY B.etID),
B.etID,
B.cNumber,
B.cName
FROM Table2 AS B
If you just want a result set, you can use:
SELECT A.tbID, A.etID, A.cNumber, A.cName
FROM Table1 A
UNION ALL
SELECT (a.maxID + ROW_NUMBER() OVER (ORDER BY (SELECT NULL))) as tbID,
B.etID, B.cNumber, B.cName
FROM Table2 B CROSS JOIN
(SELECT MAX(A.tbID) as maxID FROM Table1 as A) a;
If you are inserting these rows into a new table, then the id can be assigned automatically -- but the values might differ for A.
since I am not as good with more complex SQL SELECT Statements I thought of just asking here, since it's hard to find something right on topic.
I got two tables who have exactly the same structure like
TABLE A (id (INT(11)), time (VARCHAR(10));)
TABLE B (id (INT(11)), time (VARCHAR(10));)
Now I want a single SELECT to count the entrys of an specific id in both tables.
SELECT COUNT(*) FROM TABLE A WHERE id = '1';
SELECT COUNT(*) FROM TABLE B WHERE id = '1';
So I thought it would be much better for the database performance if I use one SELECT instead of one.
Thanks for helping out
SELECT COUNT(*) as count, 'tableA' as table_name FROM TABLEA WHERE id = '1'
union all
SELECT COUNT(*), 'tableB' FROM TABLEB WHERE id = '1'
If you want the separate counts in a single row, you can use subqueries
SELECT
(SELECT COUNT(*) FROM TABLE A WHERE id = '1') a_count,
(SELECT COUNT(*) FROM TABLE B WHERE id = '1') b_count;
You could do it like:
select count(*)
from (
select id from t1 where id = 1
union all
select id from t2 where id = 1
) as t
Another alternative is:
select sum(cnt)
from (
select count(*) as cnt from t1 where id = 1
union all
select count(*) as cnt from t2 where id = 1
) as t
I tried the sql query given below:
SELECT * FROM (SELECT *
FROM TABLE_A ORDER BY COLUMN_1)DUMMY_TABLE
UNION ALL
SELECT * FROM TABLE_B
It results in the following error:
The ORDER BY clause is invalid in views, inline functions, derived
tables, subqueries, and common table expressions, unless TOP or FOR
XML is also specified.
I need to use order by in union all. How do I accomplish this?
SELECT *
FROM
(
SELECT * FROM TABLE_A
UNION ALL
SELECT * FROM TABLE_B
) dum
-- ORDER BY .....
but if you want to have all records from Table_A on the top of the result list, the you can add user define value which you can use for ordering,
SELECT *
FROM
(
SELECT *, 1 sortby FROM TABLE_A
UNION ALL
SELECT *, 2 sortby FROM TABLE_B
) dum
ORDER BY sortby
You don't really need to have parenthesis. You can sort directly:
SELECT *, 1 AS RN FROM TABLE_A
UNION ALL
SELECT *, 2 AS RN FROM TABLE_B
ORDER BY RN, COLUMN_1
Not an OP direct response, but I thought I would jimmy in here responding to the the OP's ERROR messsage, which may point you in another direction entirely!
All these answers are referring to an overall ORDER BY once the record set has been retrieved and you sort the lot.
What if you want to ORDER BY each portion of the UNION independantly, and still have them "joined" in the same SELECT?
SELECT pass1.* FROM
(SELECT TOP 1000 tblA.ID, tblA.CustomerName
FROM TABLE_A AS tblA ORDER BY 2) AS pass1
UNION ALL
SELECT pass2.* FROM
(SELECT TOP 1000 tblB.ID, tblB.CustomerName
FROM TABLE_B AS tblB ORDER BY 2) AS pass2
Note the TOP 1000 is an arbitary number. Use a big enough number to capture all of the data you require.
There will be times when you need to do something like this :
Pull top 5 from table 1 based on a sort
and bottom 5 from table 2 based on another sort
and union these together.
solution
select * from (
-- top 5 records
select top 5 col1, col2, col3
from table1
group by col1, col2
order by col3 desc ) z
union all
select * from (
-- bottom 5 records
select top 5 col1, col2, col3
from table2
group by col1, col2
order by col3 ) z
this was the only way i was able to get around the error and worked fine for me.
SELECT * FROM (SELECT *
FROM TABLE_A ORDER BY COLUMN_1)DUMMY_TABLE
UNION ALL
SELECT * FROM TABLE_B
ORDER BY 2;
2 is column number here .. In Oracle SQL you can use the column number by which you want to sort the data
This solved my SELECT statement:
SELECT * FROM
(SELECT id,name FROM TABLE_A
UNION ALL
SELECT id,name FROM TABLE_B ) dum
order by dum.id , dum.name
where id and name columns available in tables and you can use your columns .
Simply use that , no need parenthesis or anything else
SELECT *, id as TABLE_A_ID FROM TABLE_A
UNION ALL
SELECT *, id as TABLE_B_ID FROM TABLE_B
ORDER BY TABLE_A_ID, TABLE_B_ID
ORDER BY after the last UNION should apply to both datasets joined by union.
The solution shown below:
SELECT *,id AS sameColumn1 FROM Locations
UNION ALL
SELECT *,id AS sameColumn2 FROM Cities
ORDER BY sameColumn1,sameColumn2
select CONCAT(Name, '(',substr(occupation, 1, 1), ')') AS f1
from OCCUPATIONS
union
select temp.str AS f1 from
(select count(occupation) AS counts, occupation, concat('There are a total of ' ,count(occupation) ,' ', lower(occupation),'s.') As str from OCCUPATIONS group by occupation order by counts ASC, occupation ASC
) As temp
order by f1
i would like to run a sql statement that will delete ONLY the second value for example
delete from table1 where condition1
i want this statement to delete ONLY the second value
how can i accomplish this?
i would like to clarify. i have a field called field1 which is an autonumber and and it is a primary key and it increments. i would like to delete the record containing the greater number
You could also employ the ROW_NUMBER() function of SQL server to number each row, and use this number to isolate just the second item for deletion, according to your own custom ordering in the inner query ( over (ORDER BY <myKey> asc) ). This provides a great deal of flexibility.
DELETE a FROM table1
FROM table1 a
JOIN (
select ROW_NUMBER() over (ORDER BY <myKey> asc) as AutoNumber, <myKey> from table1
) b on a.<myKey> = b.<myKey>
WHERE condition1
AND b.AutoNumber = 2
Do you want to delete only the last duplicate, or all but the first?
For all but the first: (Edited to use CTE per #Martin's suggestion.)
with target as (select * from table1 where condition1)
delete from target goner
where exists (select * from target keeper
where keeper.field1 < goner.field1)
In other words, if there is another matching record with a lower field1, delete this record.
EDIT:
To delete only the last:
with target as (select * from table1 where condition1)
delete from target goner
where exists (select * from target keeper
where keeper.field1 < goner.field1)
and not exists (select * from target missing
where missing.field1 > goner.field1)
In other words, if there is another matching record with a lower field1, AND there is no matching record with a higher field1, then we have the highest duplicate, so nuke it.
It's been a while (so my syntax my not quite be right), and this may not be the best solution, but the "academic" answer would be something like:
delete from table1 where condition1
and field1 = (select max(field1) from table1 where condition1)
Try this:
DELETE MyTable
FROM MyTable
LEFT OUTER JOIN (
SELECT MIN(id) as id, Col1, Col2, Col3
FROM MyTable
GROUP BY Col1, Col2, Col3
) as KeepRows ON
MyTable.id= KeepRows.id
WHERE
KeepRows.RowId IS NULL
UPDATE
While this might not be as "pretty" as #Jeffrey's it works. From what I can tell, #Jeffrey's does not. See sql below (Delete replaced with SELECT * for demonstration):
WITH TEMP as
(
SELECT 1 as id,'A' as a,'Z' as b
UNION
SELECT 2,'A','Z'
UNION
SELECT 3,'B','Z'
UNION
SELECT 4,'B','Z'
)
SELECT *
FROM TEMP
LEFT OUTER JOIN (
SELECT MIN(id) as id, a, b
FROM TEMP
GROUP BY a, b
) as KeepRows ON
temp.id= KeepRows.id
WHERE
KeepRows.id IS NULL