I am trying to get a simple count of all the negative and positive values of a specific column on my database. I want to be able to count these values based on another column. What would be the best way to go about handling this problem.
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Something like this:
SELECT
SUM(CASE WHEN column > 0 THEN 1 ELSE 0 END) as count_positive,
SUM(CASE WHEN column < 0 THEN 1 ELSE 0 END) as count_negative
FROM
table
You must put the column name, table name, and decide whether 0 is positive, negative or excluded (my choice)
Related
Using Microsoft SQL Server, if you use COUNT(column name) it returns the number of rows in that column which have a non-null value (i.e., it counts the rows, ignoring nulls).
Is there any way to do something similar, but allowing you to tell it which values to ignore? For example, if I wanted to count all the rows in a table which have a value which is NOT 1, I could do something like COUNTNOT(column name,1). That would count all the rows in the specified column which have a value NOT 1.
You may use conditional aggregation:
SELECT COUNT(CASE WHEN some_val <> 1 THEN 1 END) AS cnt
FROM yourTable;
The above logic is that COUNT will count one whenever some value is not equal to 1. Otherwise, it falls on the ELSE conditional, which if not present defaults to the value NULL. Since NULL is not counted, any value other than 1 would contribute zero to the count.
Why not put what you want to exclude in a WHERE clause?
SELECT COUNT(some_val) AS cnt
FROM yourTable
WHERE some_val <> 1
You need to be careful about NULL values. I would recommend:
select sum(case when column in (<values to ignore>) then 0 else 1 end)
This will count NULL values as not in the list (even if NULL is in the list). To ignore NULL values (as well), switch the logic to:
select sum(case when column not in (<values to ignore>) then 1 else 0 end)
and be sure NULL is not in the list.
I have a table named 'candidate' which contains among others columns ,score_math' and 'score_language' reflecting candidate's score in respective tests. I need to
Show the number of students who scored at least 60 in both math and language (versatile_candidates) and the number of students who scored below 40 in both of
these tests (poor_candidates). Don't include students with NULL preferred_contact. My query is:
select
count(case when score_math>=60 and score_language>=60 then 1 else 0
end) as versatile_candidates,
count(case when score_math<40 and score_language<40 then 1 else 0 end) as
poor_candidates
from candidate
where preferred_contact is not null
But this produces always total number of candidates wit not-null preferred contact type. Can't really figure out what I did wrong and more importantly why this doesn't work. [DBMS is Postgres if this matters ]Please help
You're close - the reason you're getting the total number of all candidates is because COUNT() will count a 0 the same as a 1 (and any other non-NULL value, for that matter). And since the values could only ever be 0 or 1, your COUNT() will return the total number of all candidates.
Since you're already defaulting the cases that don't match to 0, all you need to do is change the COUNT() to a SUM():
Select Sum(Case When score_math >= 60
And score_language >= 60 Then 1
Else 0
End) As versatile_candidates
, Sum(Case When score_math < 40
And score_language < 40 Then 1
Else 0
End) As poor_candidates
From candidate
Where preferred_contact Is Not Null
COUNT() does not take into consideration NULL values. All other values which are not NULL will be counted.
You might want to replace it with SUM()
im not sure about this question is already asked by anyone else or not yet because this is actually easy but my head is just still can't see the way out of this problem.
this is just like how many times that we do sampling at the material.
SELECT
TABLE01.MATERIAL_NO,
TABLE01.Sample_Tempt1,
TABLE01.Sample_Tempt2,
TABLE01.Sample_Tempt3,
TABLE01.Sample_Tempt4,
TABLE01.Sample_Tempt5
FROM
TABLE01
is it possible to create another column to show count of sample_tempt times?
i mean, if the tempt1 tempt2 data are exist, the column shows 2, when tempt2, tempt4 and tempt5 data are exist, the column show 3. and so on.
Thank you for helping me ^^
Sample :
Material no | Sample_Tempt1 | Sample_Tempt2 | Sample_Tempt3 | Sample_Tempt4 | Sample_Tempt5 |
PO1025 120 150 102
PO1026 122
For the PO1025, i want to create new column that generate "3" because the sample data that exist is only 3, for the PO1026 i want it generate "1" since the sample data that exist is only "1". quite simple right?
If "by exist" you mean "value is not NULL", then you can count the number of non-NULL values in each row as:
SELECT t1.MATERIAL_NO,
t1.Sample_Tempt1, t1.Sample_Tempt2, t1.Sample_Tempt3, t1.Sample_Tempt4, t1.Sample_Tempt5,
((case when t1.sample_temp1 is not null then 1 else 0 end) +
(case when t1.sample_temp2 is not null then 1 else 0 end) +
(case when t1.sample_temp3 is not null then 1 else 0 end) +
(case when t1.sample_temp4 is not null then 1 else 0 end) +
(case when t1.sample_temp5 is not null then 1 else 0 end)
) as NumTempts
FROM TABLE01 t1;
Note that I introduced a table alias. This makes the query easier to write and to read.
Lets say I have a table that has 50 Fields. 20 of those fields can contain the Value "YES" "NO" or "N/A". How do I query the number of "YES"s for a given row?
You write a long statement that adds up the values:
select ((case when value1 = 'Yes' then 1 else 0 end) +
(case when value2 = 'Yes' then 1 else 0 end) +
. . .
(case when value50 = 'Yes' then 1 else 0 end)
) as NumYesses
This would be much easier if you normalized the data, so each value was in a separate row. You would do this by having a separate table, called a junction or association table.
Also, you can generate this code in a spreadsheet, such as Excel, by using formulas on the columns names (or by writing a query that uses metadata in your database).
Note: this is generic ANSI SQL, because you don't specify the database. There may be some shortcuts to writing the code in different databases.
I need help making a query so I found this site for the first time and hoping someone here knows how to do it.
Lets say my database has 3 columns (Name,Type,and Decision). In the Name field there are 100 records and there can be duplicates. There are 2 different types (online and offline), and 2 kinds of decisions (Match or Mismatch).
What I need is to get a count of the matches and mismatches for each type, grouped by the Name.
The table would look like this with the columns below:
Name|Online Match Count|Online Mismatch Count|Offline Match Count|Offline Mismatch Count|
Also if any of the fields have a count of 0, I want it to display it as 0 as well.
Does anybody know how to do this? I would greatly appreciate it.
This is a common technique and is called a pivot query.
SELECT
Name,
SUM(CASE WHEN Type='online' AND Decision='Match' THEN 1 ELSE 0 END) as "Online Match Count",
SUM(CASE WHEN Type='online' AND Decision='Mismatch' THEN 1 ELSE 0 END) as "Online Mismatch Count",
SUM(CASE WHEN Type='offline' AND Decision='Match' THEN 1 ELSE 0) as "Offline Match Count",
SUM(CASE WHEN Type='offline' AND Decision='Mismatch' THEN 1 ELSE 0 END) as "Offline Mismatch Count"
FROM TableName
GROUP BY Name