Hopefully this is a simple one but I am most likely over complicating this for myself. Purpose of this code is to find previous operation name within a specified list of operations that is still open and returning it. If it's closed to say 'CLOSED'.
So far I'm using subquery to get the correct operation name, as expected I'm getting some null results which indicates to me that operation is closed. I wanted to wrap my subquery into a case statement to say something along the lines of CASE WHEN it's null then 'CLOSED' else operation_name end.
(select work_center_no
from shop_order_operation
where order_no = so.order_no
and release_no = so.release_no
and sequence_no = so.sequence_no
and work_center_no in ('CNC','EXPF','LS3M','LS4M','LS6M','PLAS','SAW','TBPL','EXSAW')
and oper_status_code in ('Released','In Process') order by operation_no fetch first 1 row only )
Above is my subquery. Hope this makes sense.
Thanks!
K
You can nicely default a value using IFNULL, just change your select clause to this:
select IFNULL(work_center_no, 'CLOSED')
Related
I currently am using this query to select some data:
SELECT DISTINCT a.code AS code, name, max(scen.Is3D) AS Is3D FROM locations LEFT JOIN .... The scen table has columns Is3D and Date. I only want to select the max of items where the date IS NOT NULL. I tried max(scen.Is3D WHERE scen.Date IS NOT NULL), but that didn't work. I cannot change anything after the FROM in my query, so I need that filtering to be done in the MAX, if possible. I am using MySQL 5.7.
You can use:
MAX(CASE WHEN scen.date IS NOT NULL THEN scen.Is3D END) AS Is3D
The CASE expression returns NULL when none of the WHEN conditions is met, but MAX() ignores null values, so this will just return the max of the Is3D columns in the selected rows.
So if we can't change anything after the FROM, then we cannot get a perfect solution here. Since you are SELECTing out the NULL values. One thing that we can try if we can only modify the final output is this.
SELECT MAX(ISNULL(scen.Date,0))...
This will replace all the NULLs with 0, but it would help to know exactly what you are trying to do. Why are you so convinced that the query itself cannot be modified in any way?
The other solution would be to put the whole query in another wrapper.
That would look like:
SELECT *
FROM (
[your whole query here]
) AS inner
WHERE inner.Date IS NOT NULL
Consider the following table:
SELECT id, Bill_Freq, Paid_From, Paid_To, Paid_Dt, rev_code FROM psr_20160708091408;
The requirement is to fetch the row which has rev_code populated with the string **SUM**.
I've also noticed that for every row with rev_code populated as **SUM** its Bill_Freq won't be either null or zero.
So I wrote two queries to fetch the row with the lowest id
Query based on string check in where clause:
select
min(id) as head_id,
bill_freq,
Paid_From,
Paid_To,
Paid_Dt
from
`psr_20160708091408` where rev_code = "**SUM**";
Query based on true condition:
select
min(id) as head_id,
bill_freq,
Paid_From,
Paid_To,
Paid_Dt
from
`psr_20160708091408` where bill_freq;
I haven't seen anyone use the second type, would like to know its reliability and circumstance of failure.
If by "second type" you mean a where clause with no explicit condition, then there is a good reason why you do not see it.
The SQL standard -- and most databases -- require explicit conditions in the where. MySQL allows the shorthand that you use but it really means:
where not billing_freq <=> 0
or equivalently:
where billing_freq <> 0 or billing_freq is null
(The <=> is the null-safe comparison operator.
The more important issue with your query is the min(). I presume that you actually want this:
select p.*
from psr_20160708091408 p
where rev_code = '**SUM**'
order by id
limit 1;
Also, you should use single quotes as string delimiters. That is the ANSI standard and there is rarely any reason to use double quotes.
Actually you can use the second type of query, but as your requirement is based on rev_code, it is always good to have condition with rev_code, because of 2 reasons
Bill_Freq having no NUlls or Zeros might be assumption based on current data
Even if it is true, in future, your application logic might change and it might have a scenario having NULL or zero, which will break your logic in future.
So my suggestion is to use first query with Rev_code
Please try to use below query
select
id,
bill_freq,
Paid_From,
Paid_To,
Paid_Dt
from
`psr_20160708091408` where rev_code = "**SUM**" ORDER BY ASC LIMIT 0,1;
Thanks.
The requirement says it itself.
The requirement is to fetch the row which has rev_code populated with
the string '**SUM**'
In the scenario that bill_freq IS NOT NULL and rev_code is populated with
the string '**SUM**' then your logic will obviously fail.
Go for
where rev_code = "**SUM**";
This case is similar to: S.O Question; mySQL returns all rows when field=0, and the Accepted answer was a very simple trick, to souround the ZERO with single quotes
FROM:
SELECT * FROM table WHERE email=0
TO:
SELECT * FROM table WHERE email='0'
However, my case is slightly different in that my Query is something like:
SELECT * FROM table WHERE email=(
SELECT my_column_value FROM myTable WHERE my_column_value=0 AND user_id =15 LIMIT 1 )
Which in a sense, becomes like simply saying: SELECT * FROM table WHERE email=0, but now with a Second Query.
PLEASE NOTE: It is a MUST that I use the SECOND QUERY.
When I tried: SELECT * FROM table WHERE email='( SELECT my_column_value FROM myTable WHERE my_column_value=0 LIMIT 1 )' (Notice the Single Quotes on the second query)
MySql SCREAMED Errors near '(.
How can this be achieved
Any Suggestion is highly honored
EDIT1: For a visual perspective of the Query
See the STEN_TB here: http://snag.gy/Rq8dq.jpg
Now, the main aim is to get the sten_h where rawscore_h = 0;
The CURRENT QUERY as a whole.
SELECT sten_h
FROM sten_tb
WHERE rawscore_h = (
SELECT `for_print_stens_rowscore`
FROM `for_print_stens_tb`
WHERE `for_print_stens_student_id` =3
AND `for_print_stens_factor_name` = 'Factor H' )
The result of the Second Query can be any number including ZERO.
Any number from >=1 Works and returns a single corresponding value from sten_h. Only =0 does not Work, it returns all rows
That's the issue.
CORRECT ANSWER OR SOLUTION FOR THIS
Just in case someone ends up in this paradox, the Accepted answer has it all.
SEE STEN_TB: http://snag.gy/Rq8dq.jpg
SEE The desired Query result here: http://snag.gy/wa4yA.jpg
I believe your issue is with implicit datatype conversions. You can make those datatype conversions explicit, to gain control.
(The "trick" with wrapping a literal 0 in single quotes, that makes the literal a string literal, rather than a numeric.)
In the more general case, you can use a CAST or CONVERT function to explicitly specify a datatype conversion. You can use an expression in place of a column name, wherever you need to...
For example, to get the value returned by my_column_value to match the datatype of the email column, assuming email is character type, something like:
... email = (SELECT CONVERT(my_column_value,CHAR(255)) FROM myTable WHERE ...
or, to get the a literal integer value to be a string value:
... FROM myTable WHERE my_column_value = CONVERT(0,CHAR(30)) ...
If email and my_column_value are just indicating true or false then they should almost certainly be both BIT NOT NULL or other two-value type that your schema uses for booleans. (Your ORM may use a particular one.) Casting is frequently a hack made necessary by a poor design.
If it should be a particular user then you shouldn't use LIMIT because tables are unordered and that doesn't return a particular user. Explain in your question what your query is supposed to return including exactly what you mean by "15th".
(Having all those similar columns is bad design: rawscore_a, sten_a, rawscore_b, sten_b,... . Use a table with two columns: rawscore, sten.)
I'm currently doing this via two separate queries from PHP, but would love to optimize and somehow in a single query.
First query..
SELECT `referrer`
FROM `tbl_traffic_log`
WHERE `domain` = 'mysite.com'
AND `referrer` != '$referringDomain'
AND CASE WHEN `clicks_in_unique`=0 THEN 2 ELSE `clicks_out_unique`/`clicks_in_unique` END < 1.4
ORDER BY RAND()
LIMIT 1
..and if mysql_num_rows shows no results, I do a second query to try again and check if there are any results minus the referrer != 'partner1.com' part.
The code is basically trying to find a random trade partner who ISN'T the partner who sent that click, but if there are no matches, as a last resort it's ok to send back, provided it matches the other criteria.
I'm pretty sure there is a way to do this, but just can't find a way after searching (probably because I'm not understanding the problem enough to type in the right thing).
Any other critique of the query is welcome as well.
Thank you :)
I think you can do this like this:
SELECT `referrer`
FROM `tbl_traffic_log`
WHERE `domain` = 'mysite.com'
AND CASE WHEN `clicks_in_unique`=0 THEN 2 ELSE `clicks_out_unique`/`clicks_in_unique` END < 1.4
ORDER BY `referrer` != '$referringDomain' desc, RAND()
LIMIT 1
The idea is to put the condition in the order by. The condition (in MySQL) evaluates to either 0 or 1, so we want where the condition is true first (hence the desc). It then chooses a random row. If there are no rows where the condition is true, then it chooses a random row.
We have a table that has either NULL or "Accepted" as values. My query returns about 250 rows.
If I add a where condition of -
AND Description = 'Accepted'
my 250 rows return in 2 seconds.
However, if I add a where condition of -
ISNULL(Description, '') = 'Accepted'
my 250 rows return in 47 seconds.
Has anyone encountered performance issues with using the ISNULL function? Unfortunately I am programatically limited to having to use ISNULL at this point.
When you include a field inside of a function, it changes how the optimizer has to run and forces it to ignore indexes.
see here: What makes a SQL statement sargable?
You can also bypass the functions entirely by using:
WHERE (Description = 'Accepted' OR Description IS NULL)
Using
ISNULL(Description, '') = 'Accepted'
in your where condition doesnt make any sense in this case. If the description is null, the original where clause of
AND Description = 'Accepted'
will still suffice.
You are basically comparing '' with 'Accepted' in every row where the description is null.
Please elaborate on what you are trying to accomplish with the query, i think you might be going in the wrong direction.
If you are trying to use this in the WHERE condition, use IS NULL, not ISNULL
SELECT field FROM table WHERE description is null
or the opposite
SELECT field FROM table WHERE NOT description is null