Can someone explain why the below doesn't work?
((SELECT COUNT(*) FROM Table1) - (SELECT Count(Metric) FROM Table1)) as X
Count(*) will give me all the rows in the table and Count(Metric) will give me the non-null values in the Metric column. So the difference between these will give me the number of null values in the Metric column and I have labelled this column X. I just want the difference between the two in Column X but not sure why it isn't working.
By the way, I know I can get it to work via the below:
SELECT COUNT(*) as a, count(metric) as b, COUNT(*)-COUNT(metric) as c
You would need to select the result:
SELECT ((SELECT COUNT(*) FROM Table1) - (SELECT Count(Metric) FROM Table1)) as X
But it is simpler to use conditional aggregation:
SELECT SUM(CASE WHEN Metrics IS NULL THEN 1 ELSE 0 END) X FROM table1
A SELECT query needs to start with SELECT (or WITH or a parenthesis if the query is a compound query with a set operator such as UNION ALL).
One method is:
SELECT ((SELECT COUNT(*) FROM Table1) - (SELECT Count(Metric) FROM Table1)) as X
A better method is:
SELECT COUNT(*) - Count(Metric) as X
FROM Table1
Not sure about amazon-redshift, but in standard SQL I would just count the records where the field is null instead of counting all minus where they are not null.
SELECT COUNT(*) FROM Table1 WHERE Metric IS NULL;
Related
SELECT AS, COUNT(*)
FROM Table1
HAVING COUNT(AS)>1
group BY AS;
This produces the result
AS COUNT
5 2
I then want to use the AS value in another query and only output the end result. Is this possible.i was thinking something like.
SELECT *
FROM
TABLE 2
Where AS =(
SELECT AS, COUNT(*)
FROM Table1
HAVING COUNT(AS)>1
group BY AS;
);
This is called a subquery. To be safe, you would use in instead of = (and as is a bad name for a column, because it is a SQL key word):
SELECT *
FROM TABLE2
WHERE col IN (SELECT col
FROM Table1
GROUP BY col
HAVING COUNT(col) > 1
);
Your first query is also incorrect, because the having clause goes after the group by.
You could use a subquery with the in operator:
SELECT *
FROM table2
WHERE AS IN (SELECT AS
FROM table1
GROUP BY AS
HAVING COUNT(*) > 1)
I need some help with a query.
I want to select row count value from a table, and then to use the value in a different query. For example:
#rowcount = select count(*) from MyTable
select A*#rowcount, B/#rowcount
from MyOtherTable
Can someone show my what is the correct syntax? I need to use #rowcount a lot of times so i prefer to calculate it only once.
In Oracle you can't mix procedural code and regular SQL like that.
But if you use this:
select a / (select count(*) from mytable),
b / (select count(*) from mytable)
from myothertable;
Oracle will evaluate the count(*) only once. There is no need to store the value somewhere to improve performance.
If you want, you could move this into a common table expression:
with row_count as (
select count(*) as numrows
from mytable
)
select a / (select numrows from row_count),
b / (select numrows from row_count)
from myothertable;
I have two queries that return one result each i.e one number
Select Count(*) as StockCountA from Table_A where dept='AAA'
Results
StockCountA
550
.
Select Count(*) as StockCountB from Table_B where dept='BBB'
Results
StockCountB
450
I wish to join the two results into one row record i.e
| StockCountA | StockCountB
| 550 | 450
You can use:
select
(Select Count(*) as StockCountA from Table_A where dept='AAA') as StockCountA,
(Select Count(*) as StockCountB from Table_B where dept='BBB') as StockCountB
Explanation: you can select single value as a field in a select statement, so you could write something like
select
x.*,
(select Value from Table_Y y) as ValueFromY
from
Table_X x
This will work only with scalar queries, meaning that the sub-query should have exactly 1 column, and at most 1 row. With 0 rows ValueFromY will return NULL and with more than 1 row, the query will fail.
An additional feature of select (in SQL Server, MySQL and probably others) is that you can select just values without specifying a table at all, like this:
Select
3.14 as MoreOrLessPI
You can combine both those facts to combine the two counts into a single result, by writing a query that looks like:
Select
(Select query that returns at most 1 row) as Result1,
(Select another query that returns at most 1 row) as Result2
This should give you the desired result:
SELECT * FROM(
(Select Count(*) as StockCountA from Table_A where dept='AAA') StockCountA ,
(Select Count(*) as StockCountB from Table_B where dept='BBB') StockCountB
);
While not always the best practice, it is possible to do a CROSS JOIN..
SELECT
COUNT(Table_A.SOME_COLUMN) as StockCountA
,COUNT(Table_B.SOME_COLUMN) as StockCountB
FROM Table_A, Table_B WHERE Table_A.dept='AAA' AND Table_B.dept='BBB'
Try below SQL :
select (Select Count(*) as StockCountA from Table_A where dept='AAA') StockCountA,
(Select Count(*) as StockCountB from Table_B where dept='BBB') StockCountB
Hope This Helps :)
I'm trying to do multiple select from diff tables and just have a result in one column.
SELECT COUNT(*) FROM tb1 union
SELECT COUNT(*) FROM tb2 union
SELECT COUNT(*) FROM tb3;
output should be like:
593643
18103600
0
Problem with this is that the result is being arranged on desc order.
Like below:
0
593643
18103600
I would want the result to be as I put the select statement.
Please advise. Btw, I'm using teradata.
Thank you.
SQL result sets are inherently unordered, unless you explicitly specify an order by clause. You can do this with a subquery:
select cnt
from ((SELECT COUNT(*) as cnt, 1 as ord FROM tb1)
union all
(SELECT COUNT(*), 2 FROM tb2)
union all
(SELECT COUNT(*), 3 FROM tb3)
) t
order by ord
If you want specific order, add ORDER BY clause. It would also be good to use UNION ALL so you always get 3 rows, even with duplicate results (two tables having the same number of rows):
SELECT 'tbl1' AS tablename, COUNT(*) AS cnt, 1 AS ord FROM tb1 UNION ALL
SELECT 'tbl2', COUNT(*), 2 FROM tb2 UNION ALL
SELECT 'tbl3', COUNT(*), 3 FROM tb3
ORDER BY ord ;
Whats wrong with this SQL?
SELECT Id, (select SUM(VALUE) from SomeTable) AS SumValue, GETDATE()
FROM MyTable
WHERE SumValue > 0
You cannot use aliased columns in the SELECT clause in the same query, except in ORDER BY.
It needs to be subqueried
SELECT Id, SumValue, GETDATE()
FROM (
SELECT Id, (select SUM(VALUE) from TABLE) AS SumValue
FROM MyTable
) X
WHERE SumValue > 0
That is the general case. For your specific query, it doesn't make sense because the subquery is not correlated to the outer query, so either NO rows show, or ALL rows show (with the same SumValue). I will simply assume you have simplified the query a lot since a table name of "table" doesn't really work.
I would probably rewrite like this:
SELECT a.Id, b.SumValue, GETDATE() as [now]
FROM MyTable a
Join
(
select id, SUM(VALUE) as [SumValue]
from [TABLE]
Group by id
)b on a.Id = b.Id
WHERE b.SumValue > 0
This is assuming that the value you are totalling relates to the ID in your table?
right way is
SELECT Id, (select SUM(VALUE) from TABLE) AS SumValue, GETDATE()
FROM MyTable
WHERE (select SUM(VALUE) from TABLE) > 0