Unable to name table dynamically at creation - c#, sqlite - c#

Using what's available in the System.Data.SQLite namespace and using C# I'm doing database operations. However, there is one problem I can't seem to get figured out.
If I want to create a table which is NAMED DYNAMICALLY AT CREATION, I thought the way to do that would be ...
command.CommandText = #"CREATE TABLE IF NOT EXISTS #tableName( ... )";
and then do this ...
command.Parameters.AddWithValue("#tableName", tableName);
and then do the
command.ExecuteNonQuery();
But what's happening is that I'm getting a new table named "#tableName" instead of whatever the variable tableName is set to.
How can I get this to work correctly?

The way that I approach problems like this is to simplify as much as I can. In this case, simple string substitution should easily resolve your problem without the need to use parameters.
For example:
command.Text = $#"CREATE TABLE IF NOT EXISTS {tableName}( ... )";
or
command.Text = string.Format(#"CREATE TABLE IF NOT EXISTS {0}( ... )", tableName);

Can you create procedure instead of inline query . you can manage easy in stored procedure like this .`CREATE PROCEDURE Dynamic_SP
#Table_Name sysname AS BEGIN
SET NOCOUNT ON;
DECLARE #DynamicSQL nvarchar(4000)
SET #DynamicSQL = N'SELECT * FROM ' + #Table_Name
EXECUTE sp_executesql #DynamicSQL END

Related

How to get custom SQL Server type into Entity Framework generated code

There is a TABLE Type defined in SQL server:
CREATE TYPE RealtySearchResult AS TABLE
(
realtyId int not null,
OwnerId int not null,
...)
And stored procedure:
CREATE PROCEDURE [dbo].[SearchRealty]
(#fulltext nvarchar(200) null,
#skipRows int,
#pageCount int,
....
)
AS
BEGIN
DECLARE #SQL nvarchar(max)
DECLARE #result RealtySearchResult
CREATE TABLE #TEMP
(
realtyId int not null,
OwnerId int not null,
...
)
set #SQL = N'
INSERT INTO #TEMP
SELECT
realty.Id AS realtyId,
realty.OwnerId,
....join with fulltext catalog.... WHERE....#pageCount .....#skipRows'
-- sp_executesql cannot write to local table variable #result,
-- that is why it reads to temp table and then to #result
exec sp_executesql #SQL, N'#skipRows int, #pageCount int', #skipRows, #pageCount
INSERT INTO #result SELECT * FROM #TEMP
SELECT * FROM #result
END
And then in Visual Studio I update the model from database and a new method (wrapper for store procedure SearchRealty) is generated, but it does not contains generated code for returning complex type.
I would expect that EntityFramework should be able to recognize that the store procedure returns defined table type RealtySearchResult and should generate wrapper for it. I am too lazy to write the complex return type by myself in C# again (I just wrote it in SQL). It is really needed?
Can I just generate wrapper for RealtySearchResult type in EntityFramework somehow?
I use Visual Studio 2017 and EntityFramework 6.
It sounds as duplicate as Stored procedure in Entity Framework database first approach but once I click the button Get Column Information I got message "The selected stored procedure or function returns no columns".
Analysis
Based on link Entity Framework not getting column info on a different schema provided by kirsten I realize that EntityFramework execute stored procedure with mode
SET FMTONLY ON
It means it strips all condition and dynamic SQL. This result in empty temporary table and procedure failing during receiving metadata from EntityFramework.
Solution
To help the designer to get metadata without dynamic SQL. Count with that conditions are removed. Following code does a job:
DECLARE #result RealtySearchResult
IF 0=1
BEGIN
SELECT * FROM #result
RETURN
END
During execution of store procedure by EntityFramework (in order to get metadata), condition 0=1 is removed and empty table of Table type is returned which is enough to get metadata. This code is never trigerred in production because of impossible condition.

SQL Server stored procedure parameter type array C# [duplicate]

How to pass an array into a SQL Server stored procedure?
For example, I have a list of employees. I want to use this list as a table and join it with another table. But the list of employees should be passed as parameter from C#.
SQL Server 2016 (or newer)
You can pass in a delimited list or JSON and use STRING_SPLIT() or OPENJSON().
STRING_SPLIT():
CREATE PROCEDURE dbo.DoSomethingWithEmployees
#List varchar(max)
AS
BEGIN
SET NOCOUNT ON;
SELECT value FROM STRING_SPLIT(#List, ',');
END
GO
EXEC dbo.DoSomethingWithEmployees #List = '1,2,3';
OPENJSON():
CREATE PROCEDURE dbo.DoSomethingWithEmployees
#List varchar(max)
AS
BEGIN
SET NOCOUNT ON;
SELECT value FROM OPENJSON(CONCAT('["',
REPLACE(STRING_ESCAPE(#List, 'JSON'),
',', '","'), '"]')) AS j;
END
GO
EXEC dbo.DoSomethingWithEmployees #List = '1,2,3';
I wrote more about this here:
Handling an unknown number of parameters in SQL Server
Ordered String Splitting in SQL Server with OPENJSON
SQL Server 2008 (or newer)
First, in your database, create the following two objects:
CREATE TYPE dbo.IDList
AS TABLE
(
ID INT
);
GO
CREATE PROCEDURE dbo.DoSomethingWithEmployees
#List AS dbo.IDList READONLY
AS
BEGIN
SET NOCOUNT ON;
SELECT ID FROM #List;
END
GO
Now in your C# code:
// Obtain your list of ids to send, this is just an example call to a helper utility function
int[] employeeIds = GetEmployeeIds();
DataTable tvp = new DataTable();
tvp.Columns.Add(new DataColumn("ID", typeof(int)));
// populate DataTable from your List here
foreach(var id in employeeIds)
tvp.Rows.Add(id);
using (conn)
{
SqlCommand cmd = new SqlCommand("dbo.DoSomethingWithEmployees", conn);
cmd.CommandType = CommandType.StoredProcedure;
SqlParameter tvparam = cmd.Parameters.AddWithValue("#List", tvp);
// these next lines are important to map the C# DataTable object to the correct SQL User Defined Type
tvparam.SqlDbType = SqlDbType.Structured;
tvparam.TypeName = "dbo.IDList";
// execute query, consume results, etc. here
}
SQL Server 2005
If you are using SQL Server 2005, I would still recommend a split function over XML. First, create a function:
CREATE FUNCTION dbo.SplitInts
(
#List VARCHAR(MAX),
#Delimiter VARCHAR(255)
)
RETURNS TABLE
AS
RETURN ( SELECT Item = CONVERT(INT, Item) FROM
( SELECT Item = x.i.value('(./text())[1]', 'varchar(max)')
FROM ( SELECT [XML] = CONVERT(XML, '<i>'
+ REPLACE(#List, #Delimiter, '</i><i>') + '</i>').query('.')
) AS a CROSS APPLY [XML].nodes('i') AS x(i) ) AS y
WHERE Item IS NOT NULL
);
GO
Now your stored procedure can just be:
CREATE PROCEDURE dbo.DoSomethingWithEmployees
#List VARCHAR(MAX)
AS
BEGIN
SET NOCOUNT ON;
SELECT EmployeeID = Item FROM dbo.SplitInts(#List, ',');
END
GO
And in your C# code you just have to pass the list as '1,2,3,12'...
I find the method of passing through table valued parameters simplifies the maintainability of a solution that uses it and often has increased performance compared to other implementations including XML and string splitting.
The inputs are clearly defined (no one has to guess if the delimiter is a comma or a semi-colon) and we do not have dependencies on other processing functions that are not obvious without inspecting the code for the stored procedure.
Compared to solutions involving user defined XML schema instead of UDTs, this involves a similar number of steps but in my experience is far simpler code to manage, maintain and read.
In many solutions you may only need one or a few of these UDTs (User defined Types) that you re-use for many stored procedures. As with this example, the common requirement is to pass through a list of ID pointers, the function name describes what context those Ids should represent, the type name should be generic.
Based on my experience, by creating a delimited expression from the employeeIDs, there is a tricky and nice solution for this problem. You should only create an string expression like ';123;434;365;' in-which 123, 434 and 365 are some employeeIDs. By calling the below procedure and passing this expression to it, you can fetch your desired records. Easily you can join the "another table" into this query. This solution is suitable in all versions of SQL server. Also, in comparison with using table variable or temp table, it is very faster and optimized solution.
CREATE PROCEDURE dbo.DoSomethingOnSomeEmployees #List AS varchar(max)
AS
BEGIN
SELECT EmployeeID
FROM EmployeesTable
-- inner join AnotherTable on ...
where #List like '%;'+cast(employeeID as varchar(20))+';%'
END
GO
Use a table-valued parameter for your stored procedure.
When you pass it in from C# you'll add the parameter with the data type of SqlDb.Structured.
See here: http://msdn.microsoft.com/en-us/library/bb675163.aspx
Example:
// Assumes connection is an open SqlConnection object.
using (connection)
{
// Create a DataTable with the modified rows.
DataTable addedCategories =
CategoriesDataTable.GetChanges(DataRowState.Added);
// Configure the SqlCommand and SqlParameter.
SqlCommand insertCommand = new SqlCommand(
"usp_InsertCategories", connection);
insertCommand.CommandType = CommandType.StoredProcedure;
SqlParameter tvpParam = insertCommand.Parameters.AddWithValue(
"#tvpNewCategories", addedCategories);
tvpParam.SqlDbType = SqlDbType.Structured;
// Execute the command.
insertCommand.ExecuteNonQuery();
}
You need to pass it as an XML parameter.
Edit: quick code from my project to give you an idea:
CREATE PROCEDURE [dbo].[GetArrivalsReport]
#DateTimeFrom AS DATETIME,
#DateTimeTo AS DATETIME,
#HostIds AS XML(xsdArrayOfULong)
AS
BEGIN
DECLARE #hosts TABLE (HostId BIGINT)
INSERT INTO #hosts
SELECT arrayOfUlong.HostId.value('.','bigint') data
FROM #HostIds.nodes('/arrayOfUlong/u') as arrayOfUlong(HostId)
Then you can use the temp table to join with your tables.
We defined arrayOfUlong as a built in XML schema to maintain data integrity, but you don't have to do that. I'd recommend using it so here's a quick code for to make sure you always get an XML with longs.
IF NOT EXISTS (SELECT * FROM sys.xml_schema_collections WHERE name = 'xsdArrayOfULong')
BEGIN
CREATE XML SCHEMA COLLECTION [dbo].[xsdArrayOfULong]
AS N'<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="arrayOfUlong">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded"
name="u"
type="xs:unsignedLong" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>';
END
GO
Context is always important, such as the size and complexity of the array. For small to mid-size lists, several of the answers posted here are just fine, though some clarifications should be made:
For splitting a delimited list, a SQLCLR-based splitter is the fastest. There are numerous examples around if you want to write your own, or you can just download the free SQL# library of CLR functions (which I wrote, but the String_Split function, and many others, are completely free).
Splitting XML-based arrays can be fast, but you need to use attribute-based XML, not element-based XML (which is the only type shown in the answers here, though #AaronBertrand's XML example is the best as his code is using the text() XML function. For more info (i.e. performance analysis) on using XML to split lists, check out "Using XML to pass lists as parameters in SQL Server" by Phil Factor.
Using TVPs is great (assuming you are using at least SQL Server 2008, or newer) as the data is streamed to the proc and shows up pre-parsed and strongly-typed as a table variable. HOWEVER, in most cases, storing all of the data in DataTable means duplicating the data in memory as it is copied from the original collection. Hence using the DataTable method of passing in TVPs does not work well for larger sets of data (i.e. does not scale well).
XML, unlike simple delimited lists of Ints or Strings, can handle more than one-dimensional arrays, just like TVPs. But also just like the DataTable TVP method, XML does not scale well as it more than doubles the datasize in memory as it needs to additionally account for the overhead of the XML document.
With all of that said, IF the data you are using is large or is not very large yet but consistently growing, then the IEnumerable TVP method is the best choice as it streams the data to SQL Server (like the DataTable method), BUT doesn't require any duplication of the collection in memory (unlike any of the other methods). I posted an example of the SQL and C# code in this answer:
Pass Dictionary to Stored Procedure T-SQL
As others have noted above, one way to do this is to convert your array to a string and then split the string inside SQL Server.
As of SQL Server 2016, there's a built-in way to split strings called
STRING_SPLIT()
It returns a set of rows that you can insert into your temp table (or real table).
DECLARE #str varchar(200)
SET #str = "123;456;789;246;22;33;44;55;66"
SELECT value FROM STRING_SPLIT(#str, ';')
would yield:
value
-----
123
456
789
246
22
33
44
55
66
If you want to get fancier:
DECLARE #tt TABLE (
thenumber int
)
DECLARE #str varchar(200)
SET #str = "123;456;789;246;22;33;44;55;66"
INSERT INTO #tt
SELECT value FROM STRING_SPLIT(#str, ';')
SELECT * FROM #tt
ORDER BY thenumber
would give you the same results as above (except the column name is "thenumber"), but sorted. You can use the table variable like any other table, so you can easily join it with other tables in the DB if you want.
Note that your SQL Server install has to be at compatibility level 130 or higher in order for the STRING_SPLIT() function to be recognized. You can check your compatibility level with the following query:
SELECT compatibility_level
FROM sys.databases WHERE name = 'yourdatabasename';
Most languages (including C#) have a "join" function you can use to create a string from an array.
int[] myarray = {22, 33, 44};
string sqlparam = string.Join(";", myarray);
Then you pass sqlparam as your parameter to the stored procedure above.
This will help you. :) Follow the next steps,
Open the Query Editor
Copy Paste the following code as it is, it will create the Function which converts the String to Int
CREATE FUNCTION dbo.SplitInts
(
#List VARCHAR(MAX),
#Delimiter VARCHAR(255)
)
RETURNS TABLE
AS
RETURN ( SELECT Item = CONVERT(INT, Item) FROM
( SELECT Item = x.i.value('(./text())[1]', 'varchar(max)')
FROM ( SELECT [XML] = CONVERT(XML, '<i>'
+ REPLACE(#List, #Delimiter, '</i><i>') + '</i>').query('.')
) AS a CROSS APPLY [XML].nodes('i') AS x(i) ) AS y
WHERE Item IS NOT NULL
);
GO
Create the Following stored procedure
CREATE PROCEDURE dbo.sp_DeleteMultipleId
#List VARCHAR(MAX)
AS
BEGIN
SET NOCOUNT ON;
DELETE FROM TableName WHERE Id IN( SELECT Id = Item FROM dbo.SplitInts(#List, ','));
END
GO
Execute this SP Using exec sp_DeleteId '1,2,3,12' this is a string of Id's which you want to delete,
You can convert your array to string in C# and pass it as a Stored Procedure parameter as below,
int[] intarray = { 1, 2, 3, 4, 5 };
string[] result = intarray.Select(x=>x.ToString()).ToArray();
 
SqlCommand command = new SqlCommand();
command.Connection = connection;
command.CommandText = "sp_DeleteMultipleId";
command.CommandType = CommandType.StoredProcedure;
command.Parameters.Add("#Id",SqlDbType.VARCHAR).Value=result ;
This will delete multiple rows in a single stored proc call. All the best.
There is no support for array in sql server but there are several ways by which you can pass collection to a stored proc .
By using datatable
By using XML.Try converting your collection in an xml format and then pass it as an input to a stored procedure
The below link may help you
passing collection to a stored procedure
Starting in SQL Server 2016 you can bring the list in as an NVARCHAR() and use OPENJSON
DECLARE #EmployeeList nvarchar(500) = '[1,2,15]'
SELECT *
FROM Employees
WHERE ID IN (SELECT VALUE FROM OPENJSON(#EmployeeList ))
I've been searching through all the examples and answers of how to pass any array to sql server without the hassle of creating new Table type,till i found this linK, below is how I applied it to my project:
--The following code is going to get an Array as Parameter and insert the values of that
--array into another table
Create Procedure Proc1
#UserId int, //just an Id param
#s nvarchar(max) //this is the array your going to pass from C# code to your Sproc
AS
declare #xml xml
set #xml = N'<root><r>' + replace(#s,',','</r><r>') + '</r></root>'
Insert into UserRole (UserID,RoleID)
select
#UserId [UserId], t.value('.','varchar(max)') as [RoleId]
from #xml.nodes('//root/r') as a(t)
END
Hope you enjoy it
Starting in SQL Server 2016 you can simply use split string
Example:
WHERE (#LocationId IS NULL OR Id IN (SELECT items from Split_String(#LocationId, ',')))
CREATE TYPE dumyTable
AS TABLE
(
RateCodeId int,
RateLowerRange int,
RateHigherRange int,
RateRangeValue int
);
GO
CREATE PROCEDURE spInsertRateRanges
#dt AS dumyTable READONLY
AS
BEGIN
SET NOCOUNT ON;
INSERT tblRateCodeRange(RateCodeId,RateLowerRange,RateHigherRange,RateRangeValue)
SELECT *
FROM #dt
END
It took me a long time to figure this out, so in case anyone needs it...
This is based on the SQL 2005 method in Aaron's answer, and using his SplitInts function (I just removed the delim param since I'll always use commas). I'm using SQL 2008 but I wanted something that works with typed datasets (XSD, TableAdapters) and I know string params work with those.
I was trying to get his function to work in a "where in (1,2,3)" type clause, and having no luck the straight-forward way. So I created a temp table first, and then did an inner join instead of the "where in". Here is my example usage, in my case I wanted to get a list of recipes that don't contain certain ingredients:
CREATE PROCEDURE dbo.SOExample1
(
#excludeIngredientsString varchar(MAX) = ''
)
AS
/* Convert string to table of ints */
DECLARE #excludeIngredients TABLE (ID int)
insert into #excludeIngredients
select ID = Item from dbo.SplitInts(#excludeIngredientsString)
/* Select recipies that don't contain any ingredients in our excluded table */
SELECT r.Name, r.Slug
FROM Recipes AS r LEFT OUTER JOIN
RecipeIngredients as ri inner join
#excludeIngredients as ei on ri.IngredientID = ei.ID
ON r.ID = ri.RecipeID
WHERE (ri.RecipeID IS NULL)

How to execute multiple statement in one line in mysql and get result into dataset

I'm developing an windows application using MySQL as data-base server.
I need to execute a prepared statement and want to load result into data-set without using stored procedure.
Can any one tell me how can i do this.
Statement
SET #Statment =
(
SELECT REPLACE(
REPLACE(
GROUP_CONCAT(
Concat(' SELECT COUNT(*) AS `ROWS`//''',TABLE_NAME,''' AS `TABLE` FROM ', TABLE_NAME , ' UNION ALL')
)
,',','')
,'//',',')
FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'wbss'
);
SET #Statment = (SELECT SUBSTRING(#Statment,1,LENGTH(#Statment) - 9));
PREPARE STMT FROM #Statment;
EXECUTE STMT;
DEALLOCATE PREPARE STMT;
Note:- I'm not having permission to do this using stored procedure.
Have you tried passing these queries as a parameter for MYSql command?try concatenating them and passing as single string. try with hard coded values to begin with.
I don't want to tell you the exact solution but may be something like this:
cmd.CommandText = "insert into animals (id, name) values (:id, :name);+
select id, name from animals where id = last_insert_id()";
Please do not consider it a literal solution.Consider it an option and make your way through it.

Handling paging and "lazy-loading" with DataSets?

My company uses raw, untyped DataSets filled via Stored Procedures exclusively. I have been tasked with finding a way to retrieve very large result sets (paging) and ways to get Lazy Loading functionality (at least I think this is lazy loading; I'm still learning that stuff to be honest) so we aren't pulling back tens of thousands of rows in one batch and hogging server resources.
I personally am not that familiar with DataSets as I avoid them whenever possible, and I would rather get rid of them entirely here, but saying "Change everything to use LINQ/EF" isn't going to be a valid answer since there's no business value to management (and it would take too long to redo things, so the idea would be shot down immediately).
Are there some resources I can look into to get this same kind of functionality but using standard untyped DataSets?
EDIT: Also, I need a solution that can work with dynamically created SQL that does not use a stored procedure.
All you need to do is to modify your stored procedure to page the result set. This of course will also mean that you'll have to pass as parameters certain criteria such as page number etc. Assuming you're using SQL Server 05 or newer, take a look at the following:
http://www.codeproject.com/KB/database/PagingResults.aspx
You'll need to implement paging inside your stored procedures. I assume you're using Sql Server, so here's a link:
http://www.davidhayden.com/blog/dave/archive/2005/12/30/2652.aspx
Note that this has nothing to do with DataSets per se. Presumably, your code generates a DataSet from a stored procedure call. If you rewrite your procs to do paging, your code will then generate a DataSet that contains only the requested page's records.
You could use the DataSet returned by your original proc to implement paging, by caching the DataSet and returning only selected rows to the client (or more accurately, using only selected rows of the DataSet to generate the client HTML), but this is a super-duper, really bad idea.
I had the same problem with asp.net 2.0 website, there is no "lazy-loading" solution to this. In order to paginate the data-sets I am using 2 sprocs that will help me wrap the paging functionality on every select I am doing.
CREATE PROCEDURE [dbo].[Generic_Counting]
#tables VARCHAR(MAX),
#filter VARCHAR(MAX) = '1=1'
AS
BEGIN
SET NOCOUNT ON;
DECLARE #strQuery VARCHAR(8000)
SET #strQuery = ' SELECT COUNT(*) FROM '+ #tables +'
WHERE '+ #filter
execute (#strQuery)
IF ##ERROR<>0
BEGIN
--error on generic count
SET NOCOUNT OFF
RETURN 10067
END
SET NOCOUNT OFF
RETURN 0
END
GO
CREATE PROCEDURE [dbo].[Generic_Paging]
#tables VARCHAR(1000),
#pk VARCHAR(100),
#pageNumber INT = 1,
#pageSize INT = 10,
#fields VARCHAR(MAX) = '*',
#filter VARCHAR(MAX) = '1=1',
#orderBy VARCHAR(MAX) = NULL
AS
BEGIN
SET NOCOUNT ON;
DECLARE #strQuery VARCHAR(8000)
DECLARE #strMinRecord VARCHAR(12);
DECLARE #strMaxRecord VARCHAR(12);
SET #strMinRecord = CONVERT(VARCHAR(12),((#pageNumber -1)*#pageSize + 1))
SET #strMaxRecord = CONVERT(VARCHAR(12), (#pageNumber * #pageSize))
-- Use ROW_NUMBER function
SET #strQuery ='
WITH Generic_CTE As
(
SELECT ''RowNumber'' = ROW_NUMBER() OVER(ORDER BY ' +
ISNULL(#orderBy,#pk) +'),' +
#fields +
' FROM ' + #tables +
' WHERE ('+ #filter +')
)
SELECT ' + #fields + '
FROM Generic_CTE
WHERE RowNumber BETWEEN ' + #strMinRecord +' AND '+ #strMaxRecord
--print #strQuery
execute (#strQuery)
IF ##ERROR<>0
BEGIN
--error on generic paging
SET NOCOUNT OFF
RETURN 10066
END
SET NOCOUNT OFF
RETURN 0
END
GO
You could take a look at the Value List Handler pattern, designed to be used where "the client requires a list of items ... for presentation. The number of items in the list is unknown and can be quite large in many instances."
The examples (in the link above and here) are for Java but should translate to asp.net fairly readily.

How do I get Linq to SQL to recognize the result set of a dynamic Stored Procedure?

I'm using Linq-to-SQL with a SQL Server backend (of course) as an ORM for a project. I need to get the result set from a stored procedure that returns from a dynamically-created table. Here's what the proc looks like:
CREATE procedure [RetailAdmin].[TitleSearch] (
#isbn varchar(50), #author varchar(50),
#title varchar(50))
as
declare #L_isbn varchar(50)
declare #l_author varchar(50)
declare #l_title varchar(50)
declare #sql nvarchar(4000)
set #L_isbn = rtrim(ltrim(#isbn))
set #l_author = rtrim(ltrim(#author))
set #l_title = rtrim(ltrim(#title))
CREATE TABLE #mytemp(
[storeid] int not NULL,
[Author] [varchar](100) NULL,
[Title] [varchar](400) NULL,
[ISBN] [varchar](50) NULL,
[Imprint] [varchar](255) NULL,
[Edition] [varchar](255) NULL,
[Copyright] [varchar](100) NULL,
[stockonhand] [int] NULL
)
set #sql = 'select a.storeid, Author,Title, thirteendigitisbn ISBN,
Imprint,Edition,Copyright ,b.stockonhand from ods.items a join ods.inventory b on
a.itemkey = b.itemkey where b.stockonhand <> 0 '
if len(#l_author) > 0
set #sql = #sql + ' and author like ''%'+#L_author+'%'''
if len(#l_title) > 0
set #sql = #sql + ' and title like ''%'+#l_title+'%'''
if len(#L_isbn) > 0
set #sql = #sql + ' and thirteendigitisbn like ''%'+#L_isbn+'%'''
print #sql
if len(#l_author) <> 0 or len(#l_title) <> 0 or len(#L_isbn) <> 0
begin
insert into #mytemp
EXECUTE sp_executesql #sql
end
select * from #mytemp
drop table #mytemp
I didn't write this procedure, but may be able to influence a change if there's a really serious problem.
My present problem is that when I add this procedure to my model, the designer generates this function:
[Function(Name="RetailAdmin.TitleSearch")]
public int TitleSearch([Parameter(DbType="VarChar(50)")] string isbn,
[Parameter(DbType="VarChar(50)")] string author,
[Parameter(DbType="VarChar(50)")] string title)
{
IExecuteResult result = this.ExecuteMethodCall(this,
((MethodInfo)(MethodInfo.GetCurrentMethod())), isbn, author, title);
return ((int)(result.ReturnValue));
}
which doesn't look anything like the result set I get when I run the proc manually:
Can anybody tell me what's going wrong here?
This is basically the same problem as this question but due to the poor phrasing from the OP it was never really answered.
Thanks Marc for your reply. I will see about making the changes you suggested.
The problem was the temp table. Linq to Sql just doesn't know what to do with them. This was particularly difficult to diagnose, because Visual Studio caches information about stored procs, so when it initially failed to find a result set it set the return as a default integer type and didn't update when I made changes to the stored proc. Getting VS to recognize a change requires you to:
Delete proc from the dbml
delete the server connection from Server Explorer
save the dbml to force a recompile
close the project and restart VS
recreate the server connection and import the proc
You might not have to do every one of those steps, but that's what worked for me. What you need to do, if you must use a temp table, is to create a barebones proc that simply returns the correct schema, and then alter it to do what you want after you've imported it into the OR Designer.
First - IMPORTANT - your SQL is vulnerable to injection; the inner command should be parameterized:
if len(#l_author) > 0
set #sql = #sql + ' and author like ''%''+#author+''%'''
EXECUTE sp_executesql #sql, N'#author varchar(100)', #L_author
This passes the value of #L_author in as the #author parameter in the dynamic command - preventing injection attacks.
Second - you don't really need the temp table. It isn't doing anything for you... you just INSERT and SELECT. Perhaps just EXEC and let the results flow to the caller naturally?
In other circumstances a table-variable would be more appropriate, but this doesn't work with INSERT/EXEC.
Are the columns the same for every call? If so, either write the dbml manually, or use a temp SP (just with "WHERE 1=0" or something) so that the SET FMT_ONLY ON can work.
If not (different columns per usage), then there isn't an easy answer. Perhaps use regular ADO.NET in this case (ExecuteReader/IDataReader - and perhaps even DataTable.Fill).
Of course, you could let LINQ take the strain... (C#):
...
if(!string.IsNullOrEmpty(author)) {
query = query.Where(row => row.Author.Contains(author));
}
...
etc
There's no real easy way to do this. I've had the same problem in the past. I think the issue is that Linq to Sql has no way of "figuring out" which type will be returned since you're building up the SELECT statement at execution time. What I did to get around this, was in the stored proc, I did just a select and selected all the columns that I possibly needed. Then, I had Linq to Sql generate the function based on that. Then, I went back to SQL and changed the stored proc back to the way it's supposed to be. The trick here is not to regenerate your DBML.

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