This is a request from my client to tweak an existing Perl script. However, it is the actual database structure on their end that confuses me.
The requirement looks pretty simple:
only pull records where _X begins with 1, 2, or 9.
However, the underlying database is not that simple, here is the guideline from their DBA:
"_X is a custom metadata field. The database stores this data in rows, not columns, within the customData table. In order to query the custom data table in an efficient manner you need to know the Field_ID for the custom field you get that from the fielddef table:
SELECT Field_ID FROM FieldDef WHERE Name = "_X";
This returns:
10012
"Now you can query CustomData. For example:
SELECT Record_ID FROM CustomData where Field_ID="10012" AND StringValue="2012-04";
He also suggests that in my case, probably it would be:
"SELECT Record_ID FROM CustomData where Field_ID="10012" AND (StringValue LIKE '1%' || StringValue LIKE '2%' || StringValue LIKE '9%')
The weird thing is that the existing Perl script doesn't contain anything like "Select Record_ID FROM" but all like "SELECT StringValue FROM".
So that is why I am very confused here: What is "store in rows, not in columns"? Why first query the Field_ID table then CustomData? I would not be able to communicate with any of them during this weekend but really wish to get some idea on the whole thing, hope experts can help me a little on sorting out the whole structure.
More info(Table schema):
http://pastebin.com/ZiDTCCC0
The existing perl script:(focus on lines 72-136)
http://pastebin.com/JHpikTeZ
Thanks in advance.
What they seem to be using is some kind of Entity-Attribute-Value model, with the entities stored as ints and explained in another table (FieldDef).
You explained pretty well how you queried it (although you can do it in one query, with a join or a subquery), and your problem seems to be that you don't know how the Perl script does it. Unfortunately, without us seeing the Perl script, we can't either :]
Related
The SQLite JSON1 extension has some really neat capabilities. However, I have not been able to figure out how I can update or insert individual JSON attribute values.
Here is an example
CREATE TABLE keywords
(
id INTEGER PRIMARY KEY,
lang INTEGER NOT NULL,
kwd TEXT NOT NULL,
locs TEXT NOT NULL DEFAULT '{}'
);
CREATE INDEX kwd ON keywords(lang,kwd);
I am using this table to store keyword searches and recording the locations from which the search was ininitated in the object locs. A sample entry in this database table would be like the one shown below
id:1,lang:1,kwd:'stackoverflow',locs:'{"1":1,"2":1,"5":1}'
The location object attributes here are indices to the actual locations stored elsewhere.
Now imagine the following scenarios
A search for stackoverflow is initiated from location index "2". In this case I simply want to increment the value at that index so that after the operation the corresponding row reads
id:1,lang:1,kwd:'stackoverflow',locs:'{"1":1,"2":2,"5":1}'
A search for stackoverflow is initiated from a previously unknown location index "7" in which case the corresponding row after the update would have to read
id:1,lang:1,kwd:'stackoverflow',locs:'{"1":1,"2":1,"5":1,"7":1}'
It is not clear to me that this can in fact be done. I tried something along the lines of
UPDATE keywords json_set(locs,'$.2','2') WHERE kwd = 'stackoverflow';
which gave the error message error near json_set. I'd be most obliged to anyone who might be able to tell me how/whether this should/can be done.
It is not necessary to create such complicated SQL with subqueries to do this.
The SQL below would solve your needs.
UPDATE keywords
SET locs = json_set(locs,'$.7', IFNULL(json_extract(locs, '$.7'), 0) + 1)
WHERE kwd = 'stackoverflow';
I know this is old, but it's like the first link when searching, it deserves a better solution.
I could have just deleted this question but given that the SQLite JSON1 extension appears to be relatively poorly understood I felt it would be more useful to provide an answer here for the benefit of others. What I have set out to do here is possible but the SQL syntax is rather more convoluted.
UPDATE keywords set locs =
(select json_set(json(keywords.locs),'$.**N**',
ifnull(
(select json_extract(keywords.locs,'$.**N**') from keywords where id = '1'),
0)
+ 1)
from keywords where id = '1')
where id = '1';
will accomplish both of the updates I have described in my original question above. Given how complicated this looks a few explanations are in order
The UPDATE keywords part does the actual updating, but it needs to know what to updatte
The SELECT json_set part is where we establish the value to be updated
If the relevant value does not exsit in the first place we do not want to do a + 1 on a null value so we do an IFNULL TEST
The WHERE id = bits ensure that we target the right row
Having now worked with JSON1 in SQLite for a while I have a tip to share with others going down the same road. It is easy to waste your time writing extremely convoluted and hard to maintain SQL in an effort to perform in-place JSON manipulation. Consider using SQLite in memory tables - CREATE TEMP TABLE... to store intermediate results and write a sequence of SQL statements instead. This makes the code a whole lot eaiser to understand and to maintain.
Hi i've hit a problem with my SQL queries, i have a table that contains 3 columns, one for vehicle brands, one for models and one for model versions.
So my data is split like
BRAND || MODEL || MODEL VERSION
RENAULT || R4 || R4 1.1 GTL
I've been asked to replace our current dropdown system with an input to make it easier for users to select their vehicle.
I'm using jQuery Autocomplete and my query looks something like this.
SELECT DISTINCT CONCAT (brand, ' ', model, ' ', version) as data from vehicles WHERE brand LIKE '%Golf%' OR model LIKE '%Golf%' OR version LIKE '%Golf%' LIMIT 5
So far so good, this will output "RENAULT R4 R4 1.1 GTL" if i type in "RENAULT"... the problem here comes when the user inserts something like Renault R4 instead of just "Renault"
As they've included the Model name as well as the Brand then it doesn't really match any of my columns in the Database and my Ajax call returns no results.
I need to query the actual result set from that concat instead so that anything the users type in will match the results, but i have no idea how i can do this.
In desperation i tried to type where data LIKE '%RENAULT R4%' but as expected this also doesn't work... What can i do in this situation? Any help would be appreciated.
Easy and slow way: Split the string by spaces and ask for each word.
SELECT ...
WHERE
(brand LIKE '%Renault%' OR model LIKE '%Renault%' OR version LIKE '%Renault%')
AND (brand LIKE '%R4%' OR model LIKE '%R4%' OR version LIKE '%R4%')
LIMIT 5
Keep in mind, that query like this one does not allow use of any index, so it is very slow.
The more complicated, but much faster implementation is to use fulltext index. You need recent version of MySQL (5.6 or newer); older versions support fulltext only on MyISAM tables which are not really a database.
CREATE FULLTEXT INDEX idx ON vehicles(brand, model, version);
SELECT ... FROM vehicles
WHERE MATCH(brand, model, version) AGAINST('Renault R4')
LIMIT 5;
(Query not tested, but you should get the idea.)
I can only think of this one, but I believe there are better ways to do it.
OR CONCAT (brand, ' ', model, ' ', version) LIKE '%RENAULT R4%'
I'm using Rails 3 with a MySQL database, and I need to programmatically create a query like this:
select * from table where category_name like '%category_name_1%'
OR category_name like '%category_name_2%'
(...snip...)
OR category_name like '%category_name_n%'
Given the table size and the project scope (500 rows at most, I think), I feel that using something like thinking sphinx would be overkill.
I know I could simply do this by writing the query string directly, but wanted to know if there's an ActiveRecord way to do this. There's no mention of this on the official guide, and I've been googling for a long while now, just to end empty-handed :(
Also, is there a reason (maybe a Rails reason?) to not to include the OR clause?
Thanks!
Assuming you have an array names with category names:
Model.where( names.map{"category_name LIKE ?"}.join(" OR "),
*names.map{|n| "%#{n}%" } )
you should google first, there is already an answer.
Look here and then here
and you'll get something like this:
accounts = Account.arel_table
Account.where(accounts[:name].matches("%#{user_name}%").or(accounts[:name].matches("%#{user_name2}%")))
If you look at the guide, they have examples that can easily be modified to this:
Client.where("orders_count = ? OR locked = ?", params[:orders], false)
Mysql has a regexp function now that can clean things up a bit, assuming there's no regex metachars in your category names:
Table.where "category_name regexp '#{names.join('|')}'"
The following doesn't work, but something like this is what I'm looking for.
select *
from Products
where Description like (#SearchedDescription + %)
SSRS uses the # operator in-front of a parameter to simulate an 'in', and I'm not finding a way to match up a string to a list of strings.
There are a few options on how to use a LIKE operator with a parameter.
OPTION 1
If you add the % to the parameter value, then you can customize how the LIKE filter will be processed. For instance, your query could be:
SELECT name
FROM master.dbo.sysobjects
WHERE name LIKE #ReportParameter1
For the data set to use the LIKE statement properly, then you could use a parameter value like sysa%. When I tested a sample report in SSRS 2008 using this code, I returned the following four tables:
sysallocunits
sysaudacts
sysasymkeys
sysaltfiles
OPTION 2
Another way to do this that doesn't require the user to add any '%' symbol is to generate a variable that has the code and exceute the variable.
DECLARE #DynamicSQL NVARCHAR(MAX)
SET #DynamicSQL =
'SELECT name, id, xtype
FROM dbo.sysobjects
WHERE name LIKE ''' + #ReportParameter1 + '%''
'
EXEC (#DynamicSQL)
This will give you finer controller over how the LIKE statement will be used. If you don't want users to inject any additional operators, then you can always add code to strip out non alpha-numeric characters before merging it into the final query.
OPTION 3
You can create a stored procedure that controls this functionality. I generally prefer to use stored procedures as data sources for SSRS and never allow dynamically generated SQL, but that's just a preference of mine. This helps with discoverability when performing dependency analysis checks and also allows you to ensure optimal query performance.
OPTION 4
Create a .NET code assembly that helps dynamically generate the SQL code. I think this is overkill and a poor choice at best, but it could work conceivably.
Have you tried to do:
select * from Products where Description like (#SearchedDescription + '%')
(Putting single quotes around the % sign?)
Dano, which version of SSRS are you using? If it's RS2000, the multi-parameter list is
not officially supported, but there is a workaround....
put like this:
select *
from tsStudent
where studentName like #SName+'%'
I know this is super old, but this came up in my search to solve the same problem, and I wound up using a solution not described here. I'm adding a new potential solution to help whomever else might follow.
As written, this solution only works in SQL Server 2016 and later, but can be adapted for older versions by writing a custom string_split UDF, and by using a subquery instead of a CTE.
First, map your #SearchedDescription into your Dataset as a single string using JOIN:
=JOIN(#SearchedDedscription, ",")
Then use STRING_SPLIT to map your "A,B,C,D" kind of string into a tabular structure.
;with
SearchTerms as (
select distinct
Value
from
string_split(#SearchedDescription, ',')
)
select distinct
*
from
Products
inner join SearchTerms on
Products.Description like SearchTerms.Value + '%'
If someone adds the same search term multiple times, this would duplicate rows in the result set. Similarly, a single product could match multiple search terms. I've added distinct to both the SearchTerms CTE and the main query to try to suppress this inappropriate row duplication.
If your query is more complex (including results from other joins) then this could become an increasingly big problem. Just be aware of it, it's the main drawback of this method.
I need to take a MySQL query and insert a string before each table name. The solution doesn't need to be one line but obviously it's a regex problem. It will be implemented in PHP so having programming logic is also fine.
Rationale and Background:
I'm revamping my code base to allow for table prefixes (eg: 'nx_users' instead of 'users') and I'd like to have a function that will automate that for me so I don't need to find every query and modify it manually.
Example:
SELECT * FROM users, teams WHERE users.team_id = teams.team_id ORDER BY users.last_name
Using the prefix 'nx_', it should change to
SELECT * FROM nx_users, nx_ teams WHERE nx_ users.team_id = nx_ teams.team_id ORDER BY nx_ users.last_name
Obviously it should handle other cases such as table aliases, joins, and other common MySQL commands.
Has anybody done this?
How big of a code base are we talking about here? A regular expression for something like this is seriously flirting with disaster and I think you're probably better off looking for every mysql_query or whatever in your code and making the changes yourself. It shouldn't take more than the hour you'd spend implementing your regex and fixing all the edge cases that it will undoubtedly miss.
Using a regex to rewrite code is going to be problematic.
If you need to dynamically change this string, then you need to separate out your sql logic into one place, and have a $table_prefix variable that is appropriately placed in every sql query. The variable can then be set by the calling code.
$query = "SELECT foo from " . $table_prefix . "bar WHERE 1";
If you are encapsulating this in a class, all the better.
This example does not take into consideration any escaping or security concerns.
First off, regular expressions alone are not up to the task. Consider things like:
select sender from email where subject like "from users group by email"
To really do this you need something that will parse the SQL, produce a parse tree which you can modify, and then emit the modified SQL from the modified parse tree. With that, it's doable, but not advisable (for the reasons Paolo gave).
A better approach would be to grep through your source looking for either the table names, the function you use to sent SQL, the word from, or something like it at script something to throw you into an editor at those points.