I am using search functionality from different tables,
already i have implemented search functionality for diiferent fields from one table by using predicate
example:-
var predicate = PredicateBuilder.True<My_prj_project>();
if (!string.IsNullOrEmpty(name))
predicate = predicate.And(e1 => e1.Prj_project_name.Equals(name));
if (!string.IsNullOrEmpty(address))
predicate = predicate.And(e1 => e1.Prj_project_address.Equals(address));
if (!string.IsNullOrEmpty(contact))
predicate = predicate.And(e1 => e1.Prj_project_contact.Equals(contact));
In this way but now i need from from tables i need to search.
So can you please send me sample (or) example
Thanks in Advance.
To make efficient searching you can also create a stored procedure inside the database and pass to it the search phrase. In stored procedure you can choose conditions, tables and fields - however you need.
Related
I have a requirement which is somewhat similar to this. My API supports a filter where there is more than 8 filter parameter. So, I want to create a query dynamically based on the filter parameter passed. I am using CriteriaBuilder to create a dynamic query.
Now, I am able to create dynamic queries successfully but the issue comes when the user wants to sort on an aggregate functions. In my query, I have 4 aggregate (count) function. So to support sorting on these columns, I just use the expression of this aggregate function but what I want is to use the alias of this expression
Repeating the expression in select and order by doesn't seem right to me. So, is there a solution/workaround to the problem. I want to declare the expression alias once and use it in both select and order by clause and if required in my group by clause in future
You probably need to build a custom projection class, you can find a decent and easy one, SQLProjectionWithAliasSupport in https://hibernate.atlassian.net/browse/HHH-2952 (from Sergey Pulyaev)
If then one wants to support also sub criteria, things get more complicate
I am writing a cypher query in neo4j that merge few seperate queries with'UNION' operator. Now, the final result need to be sorted according to a specific column and I also need to be able to use 'LIMIT' to the final result so that I can fetch based on pagination request.
How to achieve that? adding 'ORDER BY' or 'LIMIT' at the end doesn't seems to work. Can't find a way to wrap the result as temporary set(as in sql queries) either. Any suggestions?
Currently it is not possible to add a ORDER BY or SKIP/LIMIT clause to the global set of UNION.
This is a pending feature request, see https://github.com/neo4j/neo4j/issues/2725
Maybe you can share your query and we can find a way to do it without UNION ?
I have the following query:
var query = db.Prog
.Where (a => a.Prog != "00000" && a.fn != "Koll")
.Select(a => new {a.Prog, a.MEfn})
.OrderByDescending(a => a.MEfn)
The query works fine but wondering if there are general rules on the order in which you write a Lambda linq query. Meaning, .Where comes before .Select, etc.
Can somebody enlighten me on the order in which LINQ needs to be written or best practices.
There isn't a best practice on the order in which you write a LINQ query, it will depend on if you want to do your filtering first, or your projection. For example in your case, you are projecting to an anonymous type which doesn't include the 'fn' property which your filter uses, so it wouldn't be available to use in a where clause if your select was first.
A better practice would be to give your properties less cryptic names. Also, 'fn' doesn't follow the PascalCase for property names, and if it's a field then it probably shouldn't be public.
Yours can be a good order.
Let's distinguish the case where db points to an SQL DB with a very good LINQ provider and the case db is an in-memory object. I guess it's the first.
In case you are using a LINQ to SQL provider, the statements are evaluated only when you materialize the query into an object, so the SQL optimizer (inside the DB) will take care of ordering of statements.
The vice versa occurs when your statements are run against in-memory collections or to materialized collections coming from LINQ to SQL. In that case they are executed sequentially, so you want to execute first those statements that reduce the number of results in the collection. Where is the best candidate!!!
The order that they should be in are completely dependent on the context of what you are doing. So if your OrderBy is simply formatting the data to be friendly to view, put it at the end after you have trimmed your collection, if your looking for the First value of a sorted collection then maybe you would need it before the collection is iterated to get the first.
I have a search page with multiple search options(input text boxes) Based on the search criteria entered , I need to create a dynamic search query. (I need search results based on the fields for which user inputs some value)
or you can use <af:quickQuery> for a simple search. Here's the sample code taken from Oracle demo.
<af:quickQuery label="Search" id="search" searchDesc="search" binding="#{editor.component}" value="#{demoQuickQuery.queryDescriptor}" queryListener="#{demoQuickQuery.processQuery}">
</af:quickQuery>
If you are using ADF/BC, this is built-in. Just use the <af:query/> component.
af:query is the more robust of the two query components, but does require you create a viewcriteria object in the VO that will be the basis for the query. However it is very powerful: dynamically add new attributes to the query at runtime, change query rules (starts with, contains, etc)
af:quickquery allows you to choose one and only one attribute to query on at a time.
Please note: these components (and the executewithparms) are the only supported query methods in ADF Faces 11g
Hi Experts
I have a special question About dynamic Linq to Sql.
Consider we want to search in a table according two fields*(LetterNo(string) and LetterDate(Datetime))*
.OK the problem is user can enter on of that fields or even both.
I searched in the internet and found "Linq.Dynamic" library in ScottGu weblog.but in that library if we want to use SqlParameter in exported command we should use #0 and param for that.problem is I don't know how many fields user entered.
I want use one query for that and no external tool like "Linq Kit PredicateBuilder".
If I create my query string Manually(and execute using ExecuteCommand) then I will abdicate SqlParameter and risk of Sql Injenction growing up.
How Can do that?
thanks
I suspect you are wanting to do something like the following:
IQueryable<Letter> query = context.Letters;
if (!string.IsNullOrEmpty(LetterNo))
query = query.Where(letter => letter.LetterNo == LetterNo);
If (LetterDate.HasValue)
query = query.Where(letter => letter.LetterDate == LetterDate);
When you execute query, it will combine the necessary expressions and issue a single query to the database based on the user's input.