I currently have an existing database and I am using the LINQtoSQL generator tool to create the classes for me. The tool is working fine for this database and there are no errors with that tool.
When I run a LINQ to SQL query against the data, there is a row that has some invalid data somehow within the table and it is throwing a System.FormatException when it runs across this row. Does anyone know what that stems from? Does anyone know how I can narrow down the effecting column without adding them one by one to the select clause?
Do you have a varchar(1) that stores an empty string?
You need to change the type from char to string in the designer (or somehow prohibit empties). The .net char type cannot hold an empty string.
Related
I build a dynamic Dictionary in ClickHouse DB. It will create the dictionary before the SQL commands execute. Also, the dictionary name was created at the same time.
The dictionary name was a combined string by date and table name. Because I don't want to keep so much data in the long-term dictionary, the short-term Dictionary could be a great help to release the memory after maybe an hour when no one is using it.
And the error happened.
When I use the dictionary in my SQL commands it is okay with solid commands.
e.g.
dictGet(CONCAT('2022-04-06', 'MyTableName'), 'GetBackColumnName',myKeyColumn) AS col_name
But when I change to using the column from Table, it was broken.
e.g.
dictGet(CONCAT(DATE_COL, 'MyTableName'), 'GetBackColumnName',myKeyColumn) AS col_name
And the error message shows up.
Illegal type String of the first argument of function dictGet,
expected a const string.
Does anyone know how to fix the issue?
My CH version is: 20.8.7.15
I try to find the resolution from the ClickHouse office report but nothing can fix this issue. And I tried lots of functions of String to figure out what happened.
I'm changing an Oracle based SSRS report and I'm having all sorts of issues with parameters.
The connection to Oracle is OLE DB.
My code is not doing anything complicated. I've only added in a new parameter. When I only have one instance of said parameter, it runs without any issues. As soon as I add it again, it bombs.
What I'm trying to do is show records if a parameter has a match. If no match, show all records.
I can run both queries in DBVisualizer without any issues.
This is what I've done
WHERE FieldName = nvl(:parameter, FieldName)
This one doesn't return the same results as this below
WHERE FieldName = :parameter
OR :parameter IS NULL
Problem is the second WHERE clause will not run in SSRS with an OLE DB connection. We cannot use another connection manager, unfortunately.
EDIT: Thanks to Hannover Fist, I was able to get this to work by doing this
I changed my WHERE clause to
WHERE FieldName = :parameter
OR :parameter2 IS NULL
Then mapped parameter2 to pull from the same SSRS parameter as the original parameter
I haven't found a good solution to this problem but I have worked around it by declaring the parameter in the Oracle SQL and mapping it to the SSRS parameter.
Then use the parameter created in the Oracle SQL in the rest of the query. This way you'll only use each SSRS parameter once.
I have a Pesky SSRS report Problem where in the main query of my report has a condition that can have more than 1000 choices and when user selects all it will fail as my backend database is Oracle. I have done some research and found a solution that would work.
Solution is
re-writing the in clause something like this
(1,ColumnName) in ((1,Searchitem1),(1,SearchItem2))
this will work however when I do this
(1,ColumnName) in ((1,:assignedValue))
and pass just one value it works. But when I pass more than one value it fails and gives me ORA-01722: Invalid number error
I have tried multiple combination of the same in clause but nothing is working
any help is appreciated...
Wild guess: your :assignedValue is a comma-separated list of numbers, and Oracle tries to parse it as a single number.
Passing multiple values as a single value for an IN query is (almost) never a good idea - either you have to use string concatenation (prone to SQL injection and terrible performance), or you have to have a fixed number of arguments to IN (which generally is not what you want).
I'd suggest you
INSERT your search items into a temporary table
use a JOIN with this search table in your SELECT
I'm wondering if anyone has any clarification on the difference between the following statements using sqlite3 gem with ruby 1.9.x:
#db.execute("INSERT INTO table(a,b,c) VALUES (?,?,?)",
some_int, other_int, some_string)
and
#db.execute("INSERT INTO table(a,b,c) VALUES (#{some_int},"+
+"#{some_int}, #{some_string})")
My problem is: When I use the first method for insertion, I can't query for the "c" column using the following statement:
SELECT * FROM table WHERE c='some magic value'
I can use this:
"SELECT * FROM table WHERE c=?", "some magic value"
but what I really want to use is
"SELECT * FROM table WHERE c IN ('#{options.join("','")}')"
And this doesn't work with the type of inserts.
Does anyone know what the difference is at the database level that is preventing the IN from working properly?
I figured this out quite a while ago, but forgot to come back and point it out, in case someone finds this question at another time.
The difference turns out to be blobs. Apparently when you use the first form above (the substitution method using (?,?)) SQLite3 uses blogs to enter the data. However, if you construct an ordinary SQL statement, it's inserted as a regular string and the two aren't equivalent.
Insert is not possible to row query but row query used in get data that time this one working.
SQLite in you used in mobile app that time not work bat this row query you write in SQLite Browse in that work
We have a database with some fields that are varchar(max) which could contain lots of text however I have a situation where I only want to select the first for example 300 characters from the field for a paginated table of results on a MVC web site for a "preview" of the field.
for a simplified example query where I want to get all locations to display in the table
(this would be paginated, so I don't just get everything - I get maybe 10 results at a time):
return db.locations;
However this gives me a location object with all the fields containing the massive amounts of text which is very time consuming to execute.
So what I resorted to before was using SQL stored procedures with the:
LEFT(field, 300)
to resolve this issue and then in the Linq to SQL .dbml file included the stored procedure to return a "location" object for the result.
However I have many queries and I don't want to have to do this for every query.
This maybe a simple solution, but I am not sure how I can phrase this on a search engine, I would appreciate anyone who can help me with this problem.
You can use functions that directly translate to those functions too, this is useful when you need to translate code that functionally works just fine in SQL at no risk in LINQ.
Have a look at System.Data.Objects.EntityFunctions
Locations.Select(loc=>System.Data.Objects.EntityFunctions.Left(loc.Field,300))
This will get directly translated into a LEFT on the server side.
EDIT: I misread LEFT for LTRIM. Here's all the String functions that can't be used in LINQ to SQL. Have you tried String.Substring()?
Your best option is to map the stored procedure and continue using it. Here is an excellent article with screen shots showing you how to do so.
If you're not using the designer tool you can also call ExecuteCommand against the DataContext. It isn't pretty, but it's what we have for now.
I found something like this worked for me:
return from locationPart in db.locations
select new LocationPart
{
Description = locationPart.description,
Text = locationPart.text.Substring(0,300)
};
Not ideal because I have to use "select new" to return a a different object, but it seems to work.