Sub Queries in an ORDER BY clause MySQL - php

Im writing a module for an e-commerce platform that modifies the ORDER BY clause of an MySQL query.
I only have access to anything after the ORDER BY statment.
Im wanting to execute ORDER BY statements on calculated columns as such.
" ORDER BY (SELECT (shop_product.price - shop_product.sale_price) as pSavings) ASC "
Although i have no idea how i would go about this or if its even possible as i dont have access to the SELECT statement to generate the calculated columns?

If you mean this (then it is possible):
ORDER BY (shop_product.price - shop_product.sale_price) ASC

You can Try with this.
SELECT (shop_product.price - shop_product.sale_price) as pSavings ORDER BY pSavings ASC;

Related

Distinct function broken in MySQL 5.7

I have the following code that has stopped working since MySQL 5.7 upgrade:
$myDB->contentArray = $myDB->executeAssoc("
SELECT DISTINCT(YEAR(displayDate)) as year FROM
`inlineItemData_standardList`
WHERE `inlineItemGroupID` = $inlineItemGroupID
ORDER BY `displayDate` desc");
Could anyone show me how I would replace the DISTINCT part in this? I have searched around and can find others with the same issue but without a lot of PHP knowledge, I can't seem to implement the correct thing. I tried using GROUP BY 'YEAR(displayDate)) as year' but can't seem to get it to work. Thanks in advance.
The ORDER BY clause of a SELECT DISTINCT query must be consistent with the SELECT clause.
So:
SELECT DISTINCT YEAR(displayDate) as year
FROM inlineItemData_standardList
WHERE inlineItemGroupID = ?
ORDER BY YEAR(displayDate) DESC
-- Or: ORDER BY `year` DESC
Side note: use prepared statements! Do not concatenate variables in the query string: this is both inefficient and unsafe. Recommended reading: How can I prevent SQL injection in PHP?

How to order the ORDER BY using the IN() mysql? [duplicate]

I am wondering if there is away (possibly a better way) to order by the order of the values in an IN() clause.
The problem is that I have 2 queries, one that gets all of the IDs and the second that retrieves all the information. The first creates the order of the IDs which I want the second to order by. The IDs are put in an IN() clause in the correct order.
So it'd be something like (extremely simplified):
SELECT id FROM table1 WHERE ... ORDER BY display_order, name
SELECT name, description, ... WHERE id IN ([id's from first])
The issue is that the second query does not return the results in the same order that the IDs are put into the IN() clause.
One solution I have found is to put all of the IDs into a temp table with an auto incrementing field which is then joined into the second query.
Is there a better option?
Note: As the first query is run "by the user" and the second is run in a background process, there is no way to combine the 2 into 1 query using sub queries.
I am using MySQL, but I'm thinking it might be useful to have it noted what options there are for other DBs as well.
Use MySQL's FIELD() function:
SELECT name, description, ...
FROM ...
WHERE id IN([ids, any order])
ORDER BY FIELD(id, [ids in order])
FIELD() will return the index of the first parameter that is equal to the first parameter (other than the first parameter itself).
FIELD('a', 'a', 'b', 'c')
will return 1
FIELD('a', 'c', 'b', 'a')
will return 3
This will do exactly what you want if you paste the ids into the IN() clause and the FIELD() function in the same order.
See following how to get sorted data.
SELECT ...
FROM ...
WHERE zip IN (91709,92886,92807,...,91356)
AND user.status=1
ORDER
BY provider.package_id DESC
, FIELD(zip,91709,92886,92807,...,91356)
LIMIT 10
Two solutions that spring to mind:
order by case id when 123 then 1 when 456 then 2 else null end asc
order by instr(','||id||',',',123,456,') asc
(instr() is from Oracle; maybe you have locate() or charindex() or something like that)
If you want to do arbitrary sorting on a query using values inputted by the query in MS SQL Server 2008+, it can be done by creating a table on the fly and doing a join like so (using nomenclature from OP).
SELECT table1.name, table1.description ...
FROM (VALUES (id1,1), (id2,2), (id3,3) ...) AS orderTbl(orderKey, orderIdx)
LEFT JOIN table1 ON orderTbl.orderKey=table1.id
ORDER BY orderTbl.orderIdx
If you replace the VALUES statement with something else that does the same thing, but in ANSI SQL, then this should work on any SQL database.
Note:
The second column in the created table (orderTbl.orderIdx) is necessary when querying record sets larger than 100 or so. I originally didn't have an orderIdx column, but found that with result sets larger than 100 I had to explicitly sort by that column; in SQL Server Express 2014 anyways.
SELECT ORDER_NO, DELIVERY_ADDRESS
from IFSAPP.PURCHASE_ORDER_TAB
where ORDER_NO in ('52000077','52000079','52000167','52000297','52000204','52000409','52000126')
ORDER BY instr('52000077,52000079,52000167,52000297,52000204,52000409,52000126',ORDER_NO)
worked really great
Ans to get sorted data.
SELECT ...
FROM ...
ORDER BY FIELD(user_id,5,3,2,...,50) LIMIT 10
The IN clause describes a set of values, and sets do not have order.
Your solution with a join and then ordering on the display_order column is the most nearly correct solution; anything else is probably a DBMS-specific hack (or is doing some stuff with the OLAP functions in standard SQL). Certainly, the join is the most nearly portable solution (though generating the data with the display_order values may be problematic). Note that you may need to select the ordering columns; that used to be a requirement in standard SQL, though I believe it was relaxed as a rule a while ago (maybe as long ago as SQL-92).
Use MySQL FIND_IN_SET function:
SELECT *
FROM table_name
WHERE id IN (..,..,..,..)
ORDER BY FIND_IN_SET (coloumn_name, .., .., ..);
For Oracle, John's solution using instr() function works. Here's slightly different solution that worked -
SELECT id
FROM table1
WHERE id IN (1, 20, 45, 60)
ORDER BY instr('1, 20, 45, 60', id)
I just tried to do this is MS SQL Server where we do not have FIELD():
SELECT table1.id
...
INNER JOIN
(VALUES (10,1),(3,2),(4,3),(5,4),(7,5),(8,6),(9,7),(2,8),(6,9),(5,10)
) AS X(id,sortorder)
ON X.id = table1.id
ORDER BY X.sortorder
Note that I am allowing duplication too.
Give this a shot:
SELECT name, description, ...
WHERE id IN
(SELECT id FROM table1 WHERE...)
ORDER BY
(SELECT display_order FROM table1 WHERE...),
(SELECT name FROM table1 WHERE...)
The WHEREs will probably take a little tweaking to get the correlated subqueries working properly, but the basic principle should be sound.
My first thought was to write a single query, but you said that was not possible because one is run by the user and the other is run in the background. How are you storing the list of ids to pass from the user to the background process? Why not put them in a temporary table with a column to signify the order.
So how about this:
The user interface bit runs and inserts values into a new table you create. It would insert the id, position and some sort of job number identifier)
The job number is passed to the background process (instead of all the ids)
The background process does a select from the table in step 1 and you join in to get the other information that you require. It uses the job number in the WHERE clause and orders by the position column.
The background process, when finished, deletes from the table based on the job identifier.
I think you should manage to store your data in a way that you will simply do a join and it will be perfect, so no hacks and complicated things going on.
I have for instance a "Recently played" list of track ids, on SQLite i simply do:
SELECT * FROM recently NATURAL JOIN tracks;

MySQL order by ASC and DESC in same column

In MySQL is there a way to sort a column DESC for the purpose of GROUP BY but then sort that same column again ASC for the actual output? If not, then how would you recommend I re-sort them in PHP when I'm handling the results?
GROUP BY doesn't care about your order, it's running over the whole dataset anyway.

This query on mysql is taking forever to execute

im making a simple admin module to query the database to show the results. Im using this query via php:
SELECT
*
FROM myTable
WHERE id in(SELECT
id_registro
FROM myOtherTable
where id_forma='".$id_club."' and fecha_visita Like '%".$hoy."%'
)
order by id DESC
The result shows, however, it takes very long like 2 minutes..Anyone can help me out?
Thanks!
Without seeing your database, it is hard to find a way to make it faster.
Maybe you can try to turn your WHERE IN to INNER JOIN. To something like this
SELECT * FROM myTable INNER JOIN myOtherTable
ON (myTable.id = myOtherTable.id_registro)
WHERE myOtherTable.id_forma = '$id_club'
AND myOtherTable.fecha_visita LIKE '%$hoy%'
ORDER BY myTable.id DESC
Noted that you should sanitize your variable before putting it SQL query or using PDO prepare statement.
Sub Queries takes always time, so its better to ignore them as much as possible.
Try to optimize your query by checking its cardinality,possible keys getting implemented by DESC or EXPLAIN , and if necessary use FORCE INDEX over possible keys.
and I guess you can modify your query as:
SELECT
*
FROM myTable
inner join id_registro
on (id = id_forma )
where
id_forma='".$id_club."' and fecha_visita Like '%".$hoy."%'
order by id DESC
LIKE in mysql may take a long time ,with or without index.
Do u have a very large DB?

Sorting data using ORDER BY Clause in MYSQL

I have two type of deal in my form 1)One way relocation deal and 2)Regular deal.There is a table in my db -Vehicles.
vehicles table
=====================================================
id, pickuplocation, returnlocation, included location
Now when user choose One way relocation deal then in db, only id,pickuplocation,returnlocation will be inserted and the coloumn included location will be null. And when user choose Regular deal,the column pickuplocation,returnlocation wil be null only the coloumn id and included location will set.Problem is i want to sort the whole data using their location.I tried this query -
SELECT *
FROM vehicles
where 1=1
ORDER BY pickuplocation ASC,returnlocation ASC
But it will not giving proper result because some data having null in included location.how can i sort for all pickuplocation,returnlocation,exculded location
You want the IFNULL function
Try sorting by
IFNULL(returnlocation, includedlocation)
Got the solution.I used this query
(SELECT id,pickuplocation,returnlocation,deal_type FROM `vehicles` where deal_type = 1)
UNION
(SELECT id,included_location,excluded_location,deal_type FROM `vehicles` where deal_type = 2)
order by pickuplocation,returnlocation
I hope this will help someone who may run into a similar problem in the future.
SELECT *
FROM vehicles
where 1=1 AND ($condition)
ORDER BY pickuplocation ASC,returnlocation ASC
Assuming $condition will be something like field01=1 OR field2 >=1

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