I'm trying to get zip codes from zip_id's which are internally stored in companies service table below screens will give you clear idea
I have wrote this query
companies service table
Please suggest me your valuable views . Thanks in advance.
As already mentioned your database scheme is not very well designed, it violates even 1st normal form. You'd need another table where you'd store serv_area_id and zip_code (with possibly multiple rows for a signle serv_area_id) and search within this table and eventually join your original table.
Nevertheless, in order to get the result you describe you cannot use the IN operator as it operates on a value and multiple values in a form of table (either explicit via nested SELECT or enumeration literal (val1, ..., valN)). I would try some string matching as illustrated below. However, consider it rather an ugly hack than correct solution(!)
SELECT zip FROM cities_extended WHERE (
SELECT GROUP_CONCAT(',', serv_are_zipcodes)
FROM company_service_areas WHERE ...
) LIKE concat('%(', id, ')%')
Related
I'm currently thinking about a database schema in MySQL where I store SELECT queries into a certain table column, just to execute them on-the-fly when getting selected, and having the result passed instead of the actual query.
Would this be possible somehow? Or may this be bad practice? Is it even technically possible to have a result table passed to a single field, at least so I could run the query through PDO to get back a nested result array? Are there any alternatives?
I've read that this may be achieved through stored procedures, and although I grip the concept of those I can't think of how I could use those to achieve that.
You could do this, but what purpose do you have for doing it?
I would suggest using views:
The syntax should be valid when the view is created, unlike storing
the SQL in a field which may have invalid syntax.
It's easier to debug and modify.
For example, let's say one of the queries you want to store is:
SELECT product_category, COUNT(*) AS category_count
FROM product
GROUP BY product_category;
You can create a new "view" object that defines this query:
CREATE VIEW prod_cat_count AS
SELECT product_category, COUNT(*) AS category_count
FROM product
GROUP BY product_category;
Now, the object called "prod_cat_count" is stored in the database. Internally, the database just knows that "prod_cat_count" is equal to the SELECT query we mentioned. When the view is created, the database validates the syntax (checks that all columns exist, checks you haven't forgotten the GROUP BY, for example)
Then, whenever you want to get this data/run this query, you can run this statement (in SQL or in application code, for example):
SELECT product_category, category_count
FROM prod_cat_count;
If you then decide you want to change the way the product categories are counted, you can adjust the view:
SELECT product_category, COUNT(*) AS category_count
FROM product
GROUP BY product_category
ORDER BY product_category;
Hope that helps!
I basically have results grid and i have a drop down menu on my application which filters the 'Carrier' column. But when selecting a certain carrier I want all the rows returned that have the same dr_id as the Carrier which has been selected.
For example if you look at the picture attached it shows my results grid. If I filter by carrier 'ACE CALL LTD_UK' then I want rows 27, 28, 29 and 30 returned because the dr_id is the same.
Thanks
I don't have a complete solution for you as I don't know exactly what you database schema is (and it is a large stored procedure!). However I do have some suggestions/comments which you might find helpful:
I assume that the stored procedure will currently be returning a single row when they filter is set to 'ACE CALL LTD_UK', if not then this might not be relevant!
What I would do in this case would be to take you SELECT statement and put the results into a CTE, temporary table or nested query. (I'm not sure what SQL DBMS your using, looks like MSSQL, but you also have a MySQL tag for you post).
Once I have those results I would then use a LEFT JOIN from the dr_id in the temp table back to the drm table on the same column. From here you will again need to join to other tables where the data is not distinct, for example the Carrier table, then select the columns that you require.
You could do all this in the existing SELECT statement, however you will have to start joining on tables multiple times or use nested queries, which would get very messy. However the main reason why I chose the solution I have posted is because I don't know the stored procedure well enough and therefore I chose the safest solution.
If you want an example of what I mean, I will try and provide one.
I am trying to use the results of another query to use as a criteria for another. In my specific example, I might have four houses that are 'A', 'B', 'C', 'D' (the unique values of a field in a table called Homes).
I want to go through another query and say for each house type, what percent of residents (in Residents table) are married, which I want to do by using Count() to count the number for each Home type.
Do I need to loop through the results using VBA? Asking on a higher level, is there a way to use the results from a query as inputs into another - more than just limit the results of the new query to the results of the prior query?
Edit:
In semi-pseudo code:
For each (result of previous query) Do
New query WHERE field1 = (row of previous query)
End Do
What I am trying to ask, is there a way to accomplish this in Access using SQL? Or is this something that has to be done in VBA?
I know that if it can be done in SQL that would be the best performing and best practice, but I'm relatively inexperienced in SQL and online resources aren't always helpful because Access has it's own particular flavor of SQL.
Since you are using VBA to run this, you can loop through your recordsets and yes you can use a value from one query in the next query. There are alot of resources out there to help.
VBA: Working with RecordSets
Looping through Record Sets
Code through all records
To answer your general question, yes there is. You can do a nested query i.e. select column a from table a where column a = (select column b from table b where column b=x)
You can go as many levels deep as you want, but the caveat is the nested query can only return one column and with a specific answer set. You can also use select statements as your columns i.e
select (select column b from table b) col b from table a ..... Not the exact syntax but I would have to dig out some examples from an old project to find that.
Nested queries are useful, but for the level of precision you are looking for, a stored procedure or a view is probably a better option. Just for ease of use, I would look at creating a view of the data that you want and then querying from that to start with. More flexible than a nested query.
You need to join two tables using a common column and then get your specific column from any of the table
SELECT A.REQUIRED_FIELD from TABLEA AS A
INNER JOIN TABLEB AS B ON A.FOREIGN_KEY=B.FOREIGN_KEY
WHERE CONDITION
I want to try and keep this as one query and not use PHP, but it's proving to be tough.
I have a table called applications, that stores all the applications and some basic information about them.
Then, I have a table with all the types of applications in it, and that table contains a reference to another table which stores more specific data about the specific type of application in question.
select applications.id as appid, applications.category, type.title as type, type.id as tid, type.valuefld, type.tablename
from applications
left join type on applications.typeid=type.id
left join department on type.deptid=department.id
where not isnull(work_cat)
and work_cat != ''
and applications.deleted=0
and datei between '10-04-14' and '11-04-14'
order by type, work_cat
Now, in the old version, there is another query on every single result. Over hundreds of results... that sucks.
This is the query I'd like to integrate so I can get all the data in one result row. (Old is ASP, I'm re-writing it in PHP)
query = "select sum("&adors.fields("valuefld")&") as cost, description from "&adors.fields("tablename")&" where appid = '"&adors.fields("tablename")&"'"
Prepared statements, I'm aware, are the best solution, but for now they are not an option.
You can't do this with a plain SQL query - you need to have a defined set of tables that your query is based on. The fact that your current implementation queries from whatever table is named by tablename from the first result-set means that to get this all in one query, you will have to restructure your data. You have to know what tables you're querying from rather than having it dynamic.
If the reason for these different tables is the different information stored in each requiring different record (column) structures, you might want to look into Key/Value pair storage in a large table. Once you combine the dynamically named ones into a single location you can integrate your two queries together.
Is there a way that I can do a select as such
select * from attributes where product_id = 500
would return
id name description
1 wheel round and black
2 horn makes loud noise
3 window solid object you can see through
and the query
select * from attributes where product_id = 234
would return the same results as would any query to this table.
Now obviously I could just remove the where clause and go about my day. But this involves editing code that I don't really want to modify so i'm trying to fix this at the database level.
So is there a "magical" way to ignore what is in the where clause and return whatever I want using a view or something ?
Even if it was possible, I doubt it would work. Both of those WHERE clauses expect one thing to be returned, therefore the code would probably just use the first row returned, not all of them.
It would also give the database a behaviour that would make future developers pull their hair out trying to understand.
Do it properly and fix the code.
or you could pass "product_id" instead of an integer, if there's no code checking for that...so the query would become:
select * from attributes where product_id = product_id;
this would give you every row in the table.
If you can't edit the query, maybe you can append to it? You could stick
OR 1=1
on the end.
You may be able to use result set metadata to get what you want, but a result set won't have descriptions of fields. The specific API to get result set metadata from a prepared query varies by programming language, and you haven't said what language you're using.
You can query the INFORMATION_SCHEMA for the products table.
SELECT ordinal_position, column_name, column_comment
FROM INFORMATION_SCHEMA.columns
WHERE table_name = 'products' AND schema_name = 'mydatabase';
You can restructure the database into an Entity-Attribute-Value design, but that's a much more ambitious change than fixing your code.
Or you can abandon SQL databases altogether, and use a semantic data store like RDF, which allows you to query metadata of an entity in the same way you query data.
As far out as this idea seems I'm always interested in crazy ways to do things.
I think the best solution I could come up with is to use a view that uses the products table to get all the products then the attributes table to get the attributes, so every possible product is accounted for and all will get the same result