I currently have two queries, one which displays all data (regardless of time), another which considers a time frame. I'm trying to condense these together and was wondering if mysql has something for dateTimes which acts as an "allTime" variable, that is when plugged into:
select count(*) from table where (color = "red") and (dateMade between "allTime" and "allTime");
would display the row count of where color is red, for all rows in the table. A solution I thought of was to just use a minimum date of 0000-01-01 00:00:00 and some large end bound date, but if there already exists something to solve this I thought I might as well use that.
EDIT: This would be used on more than just the example query above, with most being much longer and more complex. The purpose is to combine this with node to make functions simpler and not have to consider a special case of all data, rather just use the time frame query and return all data based on the bounds given as arguments
Fill the variables #from and/or #to with NULL, if you don't want to restrict the data. Use IFNULL to check if the restriction is to be applied or not.
select count(*)
from table
where color = #color
and datemade between ifnull(#from, datemade) and ifnull(#to, datemade);
For cases when you don't need the date range you could make part of the where clause a true-ish noop:
select ...
from tablename
where date_created between $start and $end or $start = $end
Then, if you need the unbounded query, just pass the same $start and $end to it.
Don't pass the data twice unless you really have to, you could use a "conditional aggregation" instead, e.g.
select
count(*) all_count
, count(case when dateMade between #start and #end then id end) period_count
from table
where (color = "red")
To get "all time" you simply do not filter by date range in the where clause.
Note too that COUNT() function increments for any non-null value it encounters, so for the case expression it should return a column that will always be present in a row such as the primary key.
An alternative is to use SUM() instead, like this
select
count(*) all_count
, sum(case when dateMade between #start and #end then 1 else 0 end) period_count
from table
where (color = "red")
Related
I've tried looking it up, and while I think this should be possible I can't seem to find the answer I need anywhere.
I need to lookup a date from one table, then store it for use in a following query.
Below is statements that should work, with my setting the variable (which I know won't work, but I'm unsure the best way to do/show it otherwise - bar maybe querying it twice inside the if statement.)
I'm then wanting to in the latter statement, use either the date given in the second query, or if the date from the first query (that I'm thinking to set as a variable) is newer, use that instead.
startDateVariable = (SELECT `userID`, `startDate`
FROM `empDetails`
WHERE `userID` = 1);
SELECT `userID`, SUM(`weeksGROSS`) AS yearGROSS
FROM `PAYSLIP`
WHERE `date` <= "2021-11-15"
AND `date` >= IF( "2020-11-15" > startDateVariable , "2020-11-15" , startDateVariable )
AND `userID` IN ( 1 )
GROUP BY `userID`
Naturally all dates given in the query ("2021-11-15" etc) would be inserted dynamically in the prepared statement.
Now while I've set the userID IN to just query 1, it'd be ideal if I can lookup multiple users this way at once, though I can accept that I may need to make an individual query per user doing it this way.
Much appreciated!
So turns I was going about this the wrong way, looks like the best way to do this or something similar is by using SQL JOIN
This allows you to query the tables as if they are one.
I also realised rather then using an IF, i could simply make sure i was looking up newer or equal to both the date given and the start date.
Below is working as required. And allows lookup of multiple users at once as wanted.
SELECT PAYSLIP.userID, employeeDetails.startDate, SUM(PAYSLIP.weeksGROSS) AS yearGROSS
FROM PAYSLIP
INNER JOIN employeeDetails ON employeeDetails.userID=PAYSLIP.userID
WHERE PAYSLIP.date <= "2021-11-15"
AND PAYSLIP.date >= "2020-11-15"
AND PAYSLIP.date >= employeeDetails.startDate
AND PAYSLIP.userID IN ( 1,2,8 )
GROUP BY PAYSLIP.userID
See here for more usage examples: https://www.w3schools.com/sql/sql_join.asp
However along the lines of my particular question, it's possible to store variables. I.E.
SET #myvar= 'Example showing how to declare variable';
Then use it in the SQL statement by using
#myvar where you want the variable to go.
How to select COALESCE result to format( , 0)
my query is
SELECT (COALESCE((SELECT SUM(`invoices`.`paid_amount`) FROM `invoices`
WHERE DATE(`invoices`.`date`)=CURDATE()),0) +
COALESCE((SELECT SUM(`other_incomes`.`other_income_amount`) FROM `other_incomes`
WHERE DATE(`other_incomes`.`date`)=CURDATE()),0))
AS total
FROM
....
Primarily, COALESCE doesn't change the formatting. It only returns the first non-null value passed to it.
Also, instead of trying to join or do two different queries and adding, and handling all the sums and coalesces separately (not to mention the rounding), I would probably UNION all the relevant results together, then handle the coalesce/sum/round all at the end.
Try this:
SELECT round(sum(coalesce(amt, 0)), 0) as total
FROM (
SELECT paid_amount as amt
FROM invoices i
WHERE date(i.date) = CURDATE()
union all
SELECT other_income_amount
FROM other_incomes o
WHERE date(o.date) = CURDATE()
) z
Here I COALESCE first, to make nulls be 0 instead. I wrap that in a SUM to add up the values, and finally a ROUND to get the format. It was unclear from the question is you wanted to ROUND or FLOOR. If you are looking to get it with that comma, use FORMAT. Here's the mySQL documentation for that. You didn't specify your SQL flavor.
https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_format
Additionally, you should include your sql platform and version, the create statements for your tables, along with some insert statements that will provide sample data, along with the results you are looking for. It will help people answer your question. If you can include a fiddle, like https://dbfiddle.uk/, that would be nice.
I have the following case statement,
case WHEN
DATE(DATE_SUB(DATE_ADD(startDate, INTERVAL 6 MONTH),INTERVAL 1 WEEK)) = DATE(NOW()) THEN
CONCAT('You should by now have held a probationary review meeting.','You must get approval from the owners.')
END AS 'emailSentence'
The emailSentence will hold the concatenation of the two sentences. This emailSentence is referenced externally by another program.
I would like to use a different alias such as emailSentence2 and refer to the second part of concat i.e. 'You must get approval from the owners.' all within the same case statement. That would mean getting rid of concat which is fine. Is there a way of doing this ? If there is a way of doing this without using a case statement i would be happy to hear that too, but it needs to be conditional statment/function.
I do realise i can use a different case statement with the same condition but that would mean multiple case statments making the sql bloated.
SQL has a very strict syntax. With * as the only exception, listing a column in a SELECT will always look like
select ... , expression [[as] alias], ...
case will be part of expression, so it cannot span multiple columns, and cannot add/return multiple columns.
Anecdotal, SQL doesn't care too much about the code being short. For example, doing something like select <expression> as value1, <expression> as value2, value1+value2 as value3 or select <expression> as value ... where value=0 is not allowed, you would have to repeat those expressions.
Nevertheless, if you really don't want to repeat that expression, you could use a left join instead and have the comparison (once) as the on-condition:
select ..., e.emailSentence, e.emailSentence2 -- or just e.*
from ...
left join (
select
'You should by now have held a probationary review meeting.' as emailSentence,
'You must get approval from the owners.' AS emailSentence2
) e on DATE(DATE_SUB(DATE_ADD(startDate, INTERVAL 6 MONTH),INTERVAL 1 WEEK)) = DATE(NOW())
To clarify: if the on-condition is not true, the values will be null, just as in the case-version.
This solution will have it's own limitations, but might be an option for you.
I am looking for a way to use a parameter as a result that can be plugged in to another select statement later down the line.
This is the CTE select statement that I am able to pull by manually changing all four of the dates listed to what I want
SELECT CurrentYearEmp.PRCo,
CurrentYearEmp.Employee,
CASE
WHEN CurrentYearEmp.PREndDate <> '2016-11-20'
THEN '2016-11-20 00:00:00'
WHEN CurrentYearEmp.PREndDate = '2016-11-20'
THEN '2016-11-20 00:00:00'
END AS 'ParameterPREndDate'
I am able to replace the first half of the WHEN statement with a parameter like this
SELECT CurrentYearEmp.PRCo,
CurrentYearEmp.Employee,
CASE
WHEN CurrentYearEmp.PREndDate <> #PREndDate
THEN '2016-11-20 00:00:00'
WHEN CurrentYearEmp.PREndDate = #PREndDate
THEN '2016-11-20 00:00:00'
END AS 'ParameterPREndDate'
But it will only produce the results I am looking for if the parameter is 2016-11-20. I want to be able to have #PREndDate as '2017-02-14' it will post 2017-02-14 as a result of the select statement.
You can use a Table Valued Function as HABO has already said. Here is a simple example for one:
/*
--Create some dummy data in a db
CREATE TABLE SomeData
(
DataId INT IDENTITY
, Val VARCHAR(8)
, Dt DATE
)
INSERT INTO dbo.SomeData (Val, Dt) VALUES ('A', '2017-1-1'),('B', '2017-1-2'),('C', '2017-1-3'),('D', '2017-1-4'),('E', '2017-1-5')
--Create a table valued function
CREATE FUNCTION ReturnData (#StartDt DATE, #EndDt Date)
RETURNS TABLE
AS
Return
Select *
From SomeData
WHERE DT between #StartDt and #EndDt
*/
Select *
From ReturnData('1-1-2017', '1-3-2017')
The best thing IMHO about Table Functions is they can join to existing things as they are well formed objects in the database. When you do Procedures and Dynamic SQL, you get a result set but that does not mean your code can be joined. Table Functions can be cross applied to run off of cte's and they can be joined to other tables. So essentially they are better for reuse but they have rules around them so you cannot do more advanced things like dynamic sql in them(as far as I know unless they changed it recently) and other things. But if you want a reusable data set with rules governing input, that is pretty much exactly what they are made for.
I'm trying to do this query:
SELECT MAX(`peg_num`)
AS "indicator"
FROM `list`
WHERE `list_id` = 1
AND "indicator" >= 1
But I'm getting the result of NULL. What I should be getting is 99, as the range of peg_num is 00 to 99.
The value checked against "indicator" should actually be a user input, so I want it to be versatile. But, it does give me the correct result if I flip the equality around:
SELECT MAX(`peg_num`)
AS "indicator"
FROM `list`
WHERE `list_id` = 1
AND "indicator" <= 1
Why would it do this?
Edit:
As suggested, I'm using the HAVING clause... but I just ditched the alias for now anyway:
SELECT MAX(`peg_num`) AS "indicator"
FROM `list`
GROUP BY `list_id`
HAVING MAX(`peg_num`) <= 40
Still very stubborn. It gives me 99 now no matter the value in the having clause, regardless of the inequality.
Edit2:
As a clarification:
What I want to happen is the query select the largest value in the range of peg_num, but only if it is larger than a user-given input. So, the max in this case is 99. If the user wants to select a number like 101, he/she can't because it's not in the range.
Because of double quotes, "indicator" in WHERE clause is interpreted as a string. Thus, it evaluates to 0, meaning it is always less than 1. Column names must be escaped in backticks.
Keep in mind that WHERE clause is executed before SELECT an hence aliases defined in SELECT can not be used in WHERE clause.
SELECT MAX(`peg_num`) AS `indicator`
FROM `list`
WHERE `list_id` = 1
HAVING `indicator` >= 1
You might want to check out the link on the answer to another Stack question about not being allowed to use alias in where clause:
Can you use an alias in the WHERE clause in mysql?
Paul Dixon cites:
It is not allowable to refer to a column alias in a WHERE clause,
because the column value might not yet be determined when the WHERE
clause is executed. See Section B.1.5.4, “Problems with Column
Aliases”.
Also:
Standard SQL disallows references to column aliases in a WHERE clause.
The behavior you're seeing in your query when you swap the '<=' and '>=' operators, results from the query comparing the string/varchar 'indicator' to the number 1.
That's why you see the correct answer..when ('indicator' >= 1) which is true, and null when ('indicator' <= 1) which is false.
I don't know, but I'm amazed either of them work at all. WHERE works serially on fields belonging to individual records and I wouldn't expect it to work on "indicator" since that's a group calculation.
Does this do what you want?
SELECT max(`peg_num` ) AS "indicator"
FROM actions
WHERE `peg_num` >=1
AND `list_id` <= 1
WHERE happens before SELECT, and don't know what's "indicator".
You should use HAVING (with GROUP BY) to use the SELECT fields
Here's the documentation for syntax
http://dev.mysql.com/doc/refman/5.5/en/select.html
Something like this is the idea
SELECT MAX(peg_num) AS indicator
FROM list
WHERE list_id = 1
HAVING indicator <= 1
I can't test it and i never met Mysql so just the idea,
You should use HAVING
No quotes in HAVING condition
This must work:
SELECT MAX(peg_num)
AS indicator
FROM list
WHERE list_id = 1
HAVING indicator >= 1
I completely re-invented my query and it worked. The thing is, I had to use a nested query (and I wanted to not do that as much as possible, my professor had always discouraged it).
Anyway, here it is:
SELECT IF(`key` < 900, `key`, null) `key`
FROM (
(
SELECT MAX( `peg_num` ) AS `key`
FROM `list`
WHERE `list_id` =1
) AS `derivedTable`
)