I am trying to replace a column in the result of the select query as denoted in
This reference but unlike the example I have many columns in the table thus I can not specify the name of every column in the select query.
I tried some ways to attain the same but none seems effective.
select
*, (REPLACE(REPLACE(role_id,1,"admin"),2,"moderator") AS role_id
from user;
or
Select *
from user
where role_id = (select REPLACE(role_id,1,"admin") as role_id from user;
Here we assume only two possible values for the role_id however at certain instanced it might have to get data from another table ie a different table that holds different ids and values corresponding to them.
So is there a way to attain the following conditions in a single query:-
to replace values of some fields returned from select query (assuming many columns writing the names of all the columns individually is not feasible)
to get the replacement values from different tables for different columns in single table.
I need to implement the above conditions in one query but the changes shouldn't be in the database only the result of select query needs to be optimized.
Already referred to the following too but could not help.
Link 1
Link 2
Link 3
I am using phpmyadmin as engine and php as the implementation language.
If i have understood your question correctly, it's easier to use CASE/WHEN
SELECT *,
CASE WHEN role_id = 1 THEN "admin" WHEN role_id = 2 THEN "moderator" END AS role_id
FROM user;
But easier still maybe to have an array in PHP,
$roles = array("1" => "admin", "2" => "moderator", .... );
and look it up in the array. that will keep your query short and sweet. The advantage of this approach is that you don't need to change your query every time you add a new role. If you get a large number of roles (say dozens) you might actually want a separate table for that.
Related
based on my question, I have a table named tbl_programme. That table has 3 columns which are ID, session, and class. Now, I want to create an MYSQL query for a PHP website that can display the data based on the 3 columns, which are session, class, and course.
From that 2 columns, it's not compulsory to use them where clause for all 2 columns, it can be two columns or one column only. Below is my current query:
SELECT * from tbl_programme where session = '$session' AND class = '$class';
If I run the query with only put data for class and course, it still does not display the specific data that I want. I try to change the use of OR, but still the same. Can anyone help me to solve this?
Using PHP a secure user will enter a Ref (ex. NB093019) a query will be used to determine which PO(s) have that Ref and if they have any quantity. The issue is that we have 86 columns to check if that Ref is in and then once it finds what column it is in how to check the corresponding column that contains that quantity( the table cannot be edited).
I can make this work with 86 if else statements in PHP and then more if else statements inside of each PHP statement. I have no launching point once i do the initial query.
select 'remainder'as prefix, po, *comments,*GuideRef, *Qty
from remainder
where ('NB092419')IN (NWANTcomments,NWANTGuideRef,NWANTpreviouscomments,
NWANTpreviousGuideRef,NWANTprevious2comments,
NWANTprevious2GuideRef, BPrev2GuideRef,
BPrev2comments, BPrevGuideRef, BPrevcomments,
aGuideRef, Mcomments,MGuideRef,acomments,
MAGuideRef,BOGuideRef )
group by po
I have removed some of the in() information so it is not so long also the *comments, *GuideRef, *Qty would be decided by which one of the columns in the IN() statement returns information. Is this even possible
You could perhaps write an SQL that writes an SQL:
select REPLACE(
'SELECT ''{colstub}GuideRef'' as which, {colstub}Qty FROM remainder WHERE {colstub}Ref like ''%somevalue%'' UNION ALL',
'{colstub}',
REPLACE(column_name, 'GuideRef', '')
)
FROM information_schema.columns
WHERE table_name = 'remainder' and column_name LIKE '%Ref'
It works like "pull all the column names out of the info schema where the column name is like %guideref, replace guideref with nothing to get just the fragment of the column name that is varied: NWANTguideref -> NWANT, NWANTpreviousguideref -> NWANTprevious ... then uses this stub to form a query that gives a string depicting the column name, the qty from the quantity column, where the relevant guideref column is LIKE some value"
If you run this it will produce a result set like:
SELECT 'aGuideRef' as which, aQty FROM table WHERE aGuideRef LIKE '%lookingfor%' UNION ALL
SELECT 'bGuideRef' as which, bQty FROM table WHERE bGuideRef LIKE '%lookingfor% ...
So it's basically utputted a load of strings that are SQLs in themselves. It might need a bit of fine tuning, and hopefully all your columns are reliably and rigidly like xQty, xGuideRef, xComments triplets, but it essentially writes most the query for you
If you then copy the result set out of the results grid and paste it back into the query window, remove the last UNION ALL and run it, it will search the columns and tell you where it was found as well as the quantity
It's not too usable for a production system, but you could do the same in php- run the query, get the strings into another sql command, re-run it..
I would suggest you consider changing your table structure though:
prefix, qty, guideref, comments
You shouldn't have 86 columns that are the mostly same thing; you should have one column that is one of 86/3 different values then you can just query the guideref and the type. If this were an address table, I'm saying you **shouldn't* have HomeZipcode, WorkZipcode, UniversityZipcode, MomZipcode, DadZipcode.. and every time you want to store another kind of address you add more columns (BoyfriendZipcode, GirlfriendZipcode, Child1Zipcode...). Instead if you just had an "addresstype" column then you can store any number of different kinds of addresses without recompiling your app and changing your db schema
You can use this technique to re-shape the table - write an SQL that writes a bunch of UNION ALL sqls (without WHERE clauses), one of the columns should be the "recordtype" column (from colstub) and the other columns should just be "qty", "guide", "comments". Once you have your result set with the unions you can make a table to hold these 4 things, and then place INSERT INTO newtable at the head of the block of unions
I need the least expensive way to check if my url slug is formed from the values from two separate columns from two separate tables.
I will use dummy example with stores and locations to make this more human readable.
I have the following url:
www.domain.com/store-location
This could be, for example:
www.domain.com/three-words-store-chicago or
www.domain.com/nicestore-new-york-or-some-neighbourhood-with-more-words or
www.domain.com/oneword-oneword
(you get the idea)
Stores are located in table called stores, and locations in the table called locations.
All the combinations are possible in theory.
So, I would need some clever mysql query combined with php which will check if my slug (what goes after .com/) is the exact combination of store+location. So, to make it more descriptive:
url: www.domain.com/cool-store-los-angeles
Check is there "cool-store" in the table stores.slug_stores and is there "los-angeles" in the table locations.slug_location. The number of words of both is undefined as you can see above, so I don't have any possible delimiter.
IT MUST BE THE LEAST EXPENSIVE WAY because both tables tables have around 1000 lines. PLEASE HELP AND THANK YOU GUYS!
ps. IMPORTANT: I MUSTN'T CHANGE URLS IN ANY WAY
Edit: This is real project, website. Depending on the url i.e. slug I return some view with data. So I need to check for www.domain.com/nicestore-nicecity if Nicestore and Nicecity exist in tables stores and locations, and if not, or if anything else is there like www.domain.com/nicestore-nicecityBLABLA to kill that page with 404. Otherwise, if there is Nicestore and Nicecity to return some page populated with related data. I tried so far to make separate table with formed slugs like "nicestore-nicecity" and to use it for queries "SELECT whatever FROM slugs WHERE whatever = 'nicestore-nicecity' and if there is line return whatever I need to show the page ... Simplified... But, this separate table is hard to maintain. If nicestore moves to uglycity, or if it changes name, or if you add a new store or new city. I hope I was more clear now ;-)
I'm assuming that you don't have any id values on which to JOIN your tables, and that you don't have the ability to create such values. In that case, since your store/location combination could be as short as oneword-oneword, the first and last words of the slug are about as much as you can search on. You can extract the start and end parts of the slug using SUBSTRING_INDEX and use that to narrow the set of matches in each table before you try and compare the whole string. In my example, I'm using an SQL variable to store the slug:
SET #store = 'cool-store-los-angeles'
SELECT *
FROM (SELECT *
FROM stores
WHERE store LIKE CONCAT(SUBSTRING_INDEX(#store, '-', 1), '%')) s
JOIN (SELECT *
FROM locations
WHERE location LIKE CONCAT('%', SUBSTRING_INDEX(#store, '-', -1))) l
WHERE CONCAT(s.store, '-', l.location) = #store
This will return all data associated with cool-store-los-angeles assuming that such a store exists.
Demo on dbfiddle
Here's what I know about your system...
You have a stores table with column slug_stores
You have a locations table with column slug_location
I'm going to assume that each table has an id column of some type. I'm also going to assume they have a many-to-many relationship using a third junction table, something like
CREATE TABLE store_locations (
store_id <type>,
location_id <type>,
PRIMARY KEY (store_id, location_id),
FOREIGN KEY (store_id) REFERENCES stores(id),
FOREIGN KEY (location_id) REFERENCES locations(id)
);
If you don't have this sort of relationship defined, I really don't know how you maintain your store locations.
What I would suggest is creating a VIEW to calculate and represent your URLs. For example...
CREATE VIEW store_location_urls AS
SELECT
sl.store_id,
sl.location_id,
CONCAT_WS('-', s.slug_stores, l.slug_location) AS slug
FROM store_locations sl
INNER JOIN stores s ON sl.store_id = s.id
INNER JOIN locations l ON sl.location_id = l.id;
Now you can use this view to do the following...
Check if a request URL slug is valid
SELECT store_id, location_id FROM store_location_urls WHERE slug = ?
If this returns a record, you can then further query the stores and locations tables for whatever extra data you need to render your page (or even just join them in the original query). Otherwise, use
http_response_code(404);
Get all the URL slugs for a particular store
SELECT slug FROM store_location_urls WHERE store_id = ?
Similarly, you could get all the URL slugs for a particular location
An extra note... due to concatenating strings, any indexes you have on stores.slug_stores and locations.slug_location will be useless with the above VIEW. The alternative is to use a real derived table (like what you currently have) and maintain it with triggers.
I think you can query like following in mysql and if do check in php afterwards. From your description, it doesn't sound like there is any join possible between those tables so, union is required, i think.
select col1,col2 from stores where slug_stores = ?
union
select col1,col2 from locations where slug_location = ?
I'm trying to add a function to a script that orders a list of users and then allows that same order SQL to be used to create an export file. I'm writing it for a piece of software that hosts basic user data in one table, and the question value I'm trying to get in another. Here's the details:
Table1 is base_user and from it I need the values of columns id, username, and email. However, I want to add the option to order/export by users with all that same data, but by their sex.
Table2 is base_question_data and from it I want to get the question 'sex' value.
Users can pick between Male or Female (Values: 1 or 2), and that info is stored in a column named intValue. I've already tried using INNER JOINS and such selecting multiple info from both tables, but where I'm getting confused is how to say "Get id, username, email, and sex for every user that is X sex" where "X sex" is the gender the user set to order/export by. I'm having a hard time figuring out how to get the specifics for the sex value for each user, but also use it to only show all those users of that value. All ideas are appreciated.
EDIT:
Forgot to mention that in the 'base_question_data' table, column 'userId' is equal to column 'id' in 'base_user' table.
This is Table1 or base_user
This is Table2 or base_question_data
To clarify what I'm trying to do:
In the 'base_user' table, I want to select ID, Username, and Email. I have this working normally, as it's a simple query. I want to, however, let users order by each user's gender. So
1)They can order the preview list by Male (questionName = sex intValue = 1) or Female (questionName = sex intValue = 2). This way, it will show all user's ID, Username, and Email who are gender 1 or 2. Using this same query, I'm trying to let them export that data as well, so they can export only users of gender 1 or 2.
My problem is the process of combining all of this data. I need to combine base_user's "id" to base_question_data's "userId" and I need to also get the value of each user by targeting base_question_data's questionName='sex' and get the intValue based on if they're ordering by Male (value=1) or Female (value=2).
I've done LEFT JOINS when combining one value to another for two tables, and while this is still two tables, I've never done it where I need to combine two different keys from two tables while also ordering them all by two different column values in one of those tables.
I agree with #rowmoin but if you use LEFT JOIN it will give null value if no entry in your base_question_data table and if you use INNER JOIN it will ignore those records from both tables which does not match so you can not get users from base_user if you do not have related entries in base_question_data table.
The query was easier than I anticipated. I will explain it in detail here.
To achieve something like this, (in which I needed one table's two values to decide what I'm getting in my other table results), I simply changed the value of 'intValue' in my query, but you can also do this by assigning a php value to let it be dynamically changed if you want. Since I'm doing a change between 1 or 2, I just have to different queries with the respective variable.
Here's my query:
SELECT * FROM ow_base_user
INNER JOIN ow_base_question_data ON ow_base_user.id = ow_base_question_data.userId
WHERE questionName='sex' AND intValue='$value';
I finally realized this morning I needed to go backwards, rather, and select my conditionals from base_question, rather than from the base_user table. Using this query, (where $value=1 for male or $value=2 for Female) I have successfully gotten to return a list of user's who match the set $value with their IDs, Username, and Email.
I have a table in MySQL that I'm accessing from PHP. For example, let's have a table named THINGS:
things.ID - int primary key
things.name - varchar
things.owner_ID - int for joining with another table
My select statement to get what I need might look like:
SELECT * FROM things WHERE owner_ID = 99;
Pretty straightforward. Now, I'd like users to be able to specify a completely arbitrary order for the items returned from this query. The list will be displayed, they can then click an "up" or "down" button next to a row and have it moved up or down the list, or possibly a drag-and-drop operation to move it to anywhere else. I'd like this order to be saved in the database (same or other table). The custom order would be unique for the set of rows for each owner_ID.
I've searched for ways to provide this ordering without luck. I've thought of a few ways to implement this, but help me fill in the final option:
Add an INT column and set it's value to whatever I need to get rows
returned in my order. This presents the problem of scanning
row-by-row to find the insertion point, and possibly needing to
update the preceding/following rows sort column.
Having a "next" and "previous" column, implementing a linked list.
Once I find my place, I'll just have to update max 2 rows to insert
the row. But this requires scanning for the location from row #1.
Some SQL/relational DB trick I'm unaware of...
I'm looking for an answer to #3 because it may be out there, who knows. Plus, I'd like to offload as much as I can on the database.
From what I've read you need a new table containing the ordering of each user, say it's called *user_orderings*.
This table should contain the user ID, the position of the thing and the ID of the thing. The (user_id, thing_id) should be the PK. This way you need to update this table every time but you can get the things for a user in the order he/she wants using ORDER BY on the user_orderings table and joining it with the things table. It should work.
The simplest expression of an ordered list is: 3,1,2,4. We can store this as a string in the parent table; so if our table is photos with the foreign key profile_id, we'd place our photo order in profiles.photo_order. We can then consider this field in our order by clause by utilizing the find_in_set() function. This requires either two queries or a join. I use two queries but the join is more interesting, so here it is:
select photos.photo_id, photos.caption
from photos
join profiles on profiles.profile_id = photos.profile_id
where photos.profile_id = 1
order by find_in_set(photos.photo_id, profiles.photo_order);
Note that you would probably not want to use find_in_set() in a where clause due to performance implications, but in an order by clause, there are few enough results to make this fast.