In MSAccess I have a table with column
1 Col1, Col2, Col3, Col4.
I want to make this column as rows as shown below using an SQL query preferably using PIVOT TRANSFORM. Any help is appreciated!
1 Col1,
2 Col2
3 Col3
4 Col4
You need to use a UNION or UNION ALL query:
Select 1, Col1 From MyTable
Union All
Select 2, Col2 From MyTable
Union All
Select 3, Col3 From MyTable
Union All
Select 4, Col4 From MyTable
Union All will return rows from every table even if it creates duplicates. Union will effectively group the results together so that you can unique rows at a performance cost.
Related
I have the following sql at the begnging.
select col1, col2 from table1
union
select col1, col2 from table2
Now I want to able to do a count the total number of rows in the union set from above, and order by col2. How should I do this?
with a as (
select col1, col2 from table1
union
select col1, col2 from table2
)
select *,count(1) over()
from a
order by col2
;
I'm trying to write a query that pulls data from a lot of tables, and has about 20 unions. It's pulling the same information repeatedly, but with more layers each time, to show a sort of tree.
I want to compare the final two columns. I'm using a case to do this, and if I add a case to this query then I get the error "query block has incorrect number of results columns". This seems to be because the final select in the union has an extra column (the compare case).
Is there any way to work around this? I don't want to add the case to each select, as this would add about 15 more columns that I don't want.
Use a sub-query:
SELECT col1,
col2,
CASE
WHEN col1 = 'somevalue'
THEN 'someresult'
ELSE 'otherresult'
END AS col3
FROM (
SELECT col1, col2 FROM table1 UNION ALL
SELECT col1, col2 FROM table2 UNION ALL
SELECT col1, col2 FROM table3
-- ...
);
Or use a sub-query factoring clause:
WITH data ( col1, col2 ) AS (
SELECT col1, col2 FROM table1 UNION ALL
SELECT col1, col2 FROM table2 UNION ALL
SELECT col1, col2 FROM table3
-- ...
)
SELECT col1,
col2,
CASE
WHEN col1 = 'somevalue'
THEN 'someresult'
ELSE 'otherresult'
END AS col3
FROM data;
I am trying to combine three tables in an SQLite database into one new combined table. The three tables have the same column names, but the third table is missing one of the columns. Here is how I am trying to do it:
CREATE TABLE cobmined
AS
SELECT col1, col2, col3
FROM
(
SELECT col1, col2, col3 from table1
UNION ALL
SELECT col1, col2, col3 from table2
UNION ALL
SELECT col1, col2 from table3
) s
;
This works when doing this only on the first two tables, when adding the third table I get the message:
SELECTs to the left and right of UNION do not have the same number of result columns
Is there a way to let SQL ignore the missing column and leave it with NULLs if needed?
Add a NULL value to the third table
CREATE TABLE cobmined
AS
SELECT col1, col2, col3
FROM
(
SELECT col1, col2, col3 from table1
UNION ALL
SELECT col1, col2, col3 from table2
UNION ALL
SELECT col1, col2, null from table3
) s
;
Also, no need for sub-query
CREATE TABLE cobmined
AS
SELECT col1, col2, col3 from table1
UNION ALL
SELECT col1, col2, col3 from table2
UNION ALL
SELECT col1, col2, null from table3
I want to note that you don't need the subquery:
CREATE TABLE combined AS
SELECT col1, col2, col3 from table1
UNION ALL
SELECT col1, col2, col3 from table2
UNION ALL
SELECT col1, col2, NULL from table3;
In addition, you may find that a view is more suitable for your purposes than an actual table.
I have 2 SQL's and the result come fine. They are no relation between those 2 queries but I want to see all the rows in single column.
e.g.
Select col1,col2,sum(col3) as col3 from table a
select col4,col5 from table b
I would like the result to be
col1 col2 col3 col4 col5
If there is no equivalent row for either table a or table b replace with zeroes.
Could some one help me with this. thanks.
Since, you didn't provided any information like table structure or data inside each tables. You can cross join both tables.
select t.col1,t.col2,t.col3,t1.col1,t1.col2 from tab1 t,tab2 t1;
SQLFiddle
In both select statements add column based on rownum or row_number() and then full join results using this column:
select nvl(col1, 0) col1, nvl(col2, 0) col2, nvl(col3, 0) col3,
nvl(col4, 0) col4, nvl(col5, 0) col5
from
(select rownum rn, col1, col2, col3 from (
select col1, col2, sum(col3) col3 from tableA group by col1, col2)) a
full join (select rownum rn, col4, col5 from tableB) b using (rn)
SQLFiddle demo
I guess a UNION could be a pragmatic solution since the 2 queries are not related. They are just 2 data sets that should be retrieved in one statement:
Select col1,col2,sum(col3) as col3 from table a
UNION
select col4,col5, to_number(null) col6 from table b
Be aware of col6 in the example. SQL insists on retrieving an equal set of columns in a UNION statement. It is a good practice to retrieve columns with exactly the same datatype. Since the sum(col3) will yield a number datatype column, col6 should too.
The outcome of col4 and col5 will be shown in col1 and col2.
I think I have a misunderstanding of how NOT EXISTS work and hope it can be clarified to me.
Here is the sample code I am running (also on SQL Fiddle)
select sum(col1) col1, sum(col2) col1, sum(col3) col3
from (
select 1 col1, 1 col2, 1 col3
from dual tbl1
)
where not exists(
select 2 col1, 1 col2, 1 col3
from dual tbl2
)
I thought that it should return:
1, 1, 1
But instead it returns nothing.
I make this assumption only on the fact that I though NOT EXISTS would give me a list of all the rows in the first query that do not exist in the second query (in this case 1,1,1)
Why does this not work
What would be the appropriate way to make it work the way I am expecting it to?
You are performing an uncorrelated subquery in your NOT EXISTS() condition. It always returns exactly one row, therefore the NOT EXISTS condition is never satisfied, and your query returns zero rows.
Oracle has a rowset difference operator, MINUS, that should do what you wanted:
select sum(col1) col1, sum(col2) col1, sum(col3) col3
from (
select 1 col1, 1 col2, 1 col3
from dual tbl1
MINUS
select 2 col1, 1 col2, 1 col3
from dual tbl2
)
SQL Server has an EXCEPT operator that does the same thing as Oracle's MINUS. Some other databases implement one or the other of these.
EXISTS just returns true if a record exists in the result set; it does not do any value checking. Since the sub-query returns one record, EXISTS is true, NOT EXISTS is false, and you get no records in your result.
Typically you have a WHERE cluase in the sub-query to compare values to the outer query.
One way to accomplish what you want is to use EXCEPT:
select sum(col1) col1, sum(col2) col1, sum(col3) col3
from (
select 1 col1, 1 col2, 1 col3
from dual tbl1
)
EXCEPT(
select 2 col1, 1 col2, 1 col3
from dual tbl2
)
A not exists that includes a select from dual will never return anything. Not exists will exclude rows where the embedded SQL returns something. Normally not exists should be used more like this:
select ... from MY_TABLE A where not exists (select 1 from OTHER_TABLE B where A.SOME_COL = B.SOME_COL)
As using NOT EXISTS is not good approach as it is return only single row so try it with MINUS or EXCEPT
select sum(col1) col1, sum(col2) col1, sum(col3) col3 from ( select 1 col1, 1 col2, 1 col3 from dual tbl1 MINUS select 2 col1, 1 col2, 1 col3 from dual tbl2 )
select sum(col1) col1, sum(col2) col1, sum(col3) col3 from ( select 1 col1, 1 col2, 1 col3 from dual tbl1 ) EXCEPT( select 2 col1, 1 col2, 1 col3 from dual tbl2 )