I am trying to alter an existing programm in VB , I am not experienced in this language , but unfortunately I cannot convert it for now.
I created the DB Connections with the Designer , which automatically created the BindingSource, TableAdapter , DataSet .
I insert something into this table like this :
Me.Validate()
myBindingSource.EndEdit()
myTableAdapter.Insert(1, 1, "test", 100, Now, 1, Now)
I would now like to get CURRENT_SEED valuer for the ID field ( which is Autoincrement )
can I do it somehow here without making some extra connection , is it returned somewhere ?
Regards
Robert
If you want to use table adapters for ease, just created a "Select Max(ID) From myTable" scalar query then just call it to get the last value.
int resultID = myTableAdapter.GetLastID();
Related
I have a pair of databases (one mssql and one oracle), ran by different teams. Some data are now being synchronized regularily by a stored procedure in the mssql table. This stored procedure is calling a very large
MERGE [mssqltable].[Mytable] as s
USING THEORACLETABLE.BLA as t
ON t.[R_ID] = s.[R_ID]
WHEN MATCHED THEN UPDATE SET [Field1] = s.[Field1], ..., [Brokenfield] = s.[BrokenField]
WHEN NOT MATCHED BY TARGET THEN
... another big statement
Field Brokenfield was a numeric one until today, and could take value NULL, 0, 1, .., 24
Now, the oracle team introduced a breaking change today for some reason, changed the type of the column to string and now has values NULL, "", "ALFA", "BRAVO"... in the column. Of course, the sync got broken.
What is the easiest way to fix the sync here? I (Mysql team lead, frontend expert but not so in databases) would usually apply one of our database expert guys here, but all of them are now ill, and the fix must go online today....
I thought of a stored procedure like CONVERT_BROKENFIELD_INT_TO_STRING or so, based on some switch-case, which could be called in that merge statement, but not sure how to do that.
Edit/Clarification:
What I need is a way to make a chunk of SQL code (stored procedure), taking an input of "ALFA" and returning 1, "BRAVO" -> 2, etc. and which can be reused, to avoid writing huge ifs in more then one place.
If you can not simplify the logic for correct values the way #RichardHansell desribed, you can create a crosswalk table for BrokenField to the correct values. Then you can use a common table expression or subquery with a left join to that crosswalk to use in the merge.
create table dbo.BrokenField_Crosswalk (
BrokenField varchar(32) not null primary key
, CorrectedValue int
);
insert into dbo.BrokenField_Crosswalk (BrokenField,CorrectedValue) values
('ALFA', 1)
, ('ALPHA', 1)
, ('BRAVO', 2)
...
go
And your code for the merge would look something like this:
;with cte as (
select o.R_ID
, o.Field1
, BrokenField = cast(isnull(c.CorrectedValue,o.BrokenField) as int)
....
from oracle_table.bla as o
left join dbo.BrokenField_Crosswalk as c
)
merge into [mssqltable].[Mytable] t
using cte as s
on t.[R_ID] = s.[R_ID]
when matched
then update set
[Field1] = s.[Field1]
, ...
, [Brokenfield] = s.[BrokenField]
when not matched by target
then
If they are using names with a letter at the start that goes in a sequence:
A = 1
B = 2
C = 3
etc.
Then you could do something like this:
MERGE [mssqltable].[Mytable] as s
USING THEORACLETABLE.BLA as t
ON t.[R_ID], 1)) - ASCII('A') + 1 = s.[R_ID]
WHEN MATCHED THEN UPDATE SET [Field1] = s.[Field1], ..., [Brokenfield] = s.[BrokenField]
WHEN NOT MATCHED BY TARGET THEN
... another big statement
Edit: but actually I re-read your question and you are talking about [Brokenfield] being the problem column, so my solution wouldn't work.
I don't really understand now, as it seems as though the MERGE statement is updating the oracle table with numbers, so surely you need the mapping to work the other way, i.e. 1 -> ALFA, 2 -> BETA, etc.?
I am not sure if this is possible but I have not been able to come across clear documentation for this use case. I am using F# 4 and the FSharp.Data.SqlClient library to connect to SQL Server 2016. I am wanting to call a stored procedure that returns multiple tables and turn those tables into the corresponding records. In this case the first table is made up of items and the second table is made up of customers.
My instinct is that it should look something like this:
let items, customers = cmd.Execute()
My gut is that items would be an IEnumerable<item> and customers would be an IEnumerable<customer> where item and customer are both Record types. What it appears is happening though is that FSharp.Data.SqlClient is only seeing the first returned table from the stored procedure. I am working on a SQL Server 2016 Developer instance. Here is the T-SQL to setup the example:
create table Item (
ItemID int identity(1, 1) primary key,
ItemName nvarchar(50)
)
go
create table Customer (
CustomerID int identity(1, 1) primary key,
CustomerName nvarchar(50)
)
go
insert into Item (ItemName) values ('A');
insert into Item (ItemName) values ('B');
insert into Item (ItemName) values ('C');
insert into Customer (CustomerName) values ('Gary');
insert into Customer (CustomerName) values ('Sergei');
insert into Customer (CustomerName) values ('Elise');
go
create procedure dbo.ExampleProcedure
as
begin
set nocount on;
select
ItemID,
ItemName
from Item
select
CustomerID,
CustomerName
from Customer
end;
And here is the F# script that I am testing with. It shows what I would like to be able to do but I get a compile error on the last line:
#r "../packages/FSharp.Data.SqlClient.1.8.2/lib/net40/FSharp.Data.SqlClient.dll"
#r "../packages/FSharp.Data.2.3.2/lib/net40/FSharp.Data.dll"
#r "System.Xml.Linq.dll"
open FSharp.Data
[<Literal>]
let connStr =
"Data Source=**connection string**;"
type queryExample = SqlProgrammabilityProvider<connStr>
do
use cmd = new queryExample.dbo.ExampleProcedure(connStr)
let items, customers = cmd.Execute()
I am wanting items to correspond to the first returned table and customers to correspond to the second returned table. The intellisense suggests that FSharp.Data.SqlClient is only seeing the first table. When I hover over cmd.Execute() the popup says "This expression was expected to have type 'a*'b but here has type System.Collections.Generic.IEnumerable<SqlProgrammabilityProvider<...>.dbo.ExampleProcedure.Record>". If I do the following I get access to the Items query in the stored procedure:
// Learn more about F# at http://fsharp.org. See the 'F# Tutorial' project
// for more guidance on F# programming.
#r "../packages/FSharp.Data.SqlClient.1.8.2/lib/net40/FSharp.Data.SqlClient.dll"
#r "../packages/FSharp.Data.2.3.2/lib/net40/FSharp.Data.dll"
#r "System.Xml.Linq.dll"
open FSharp.Data
[<Literal>]
let connStr =
"Data Source=**connection string**;"
type queryExample = SqlProgrammabilityProvider<connStr>
do
use cmd = new queryExample.dbo.ExampleProcedure(connStr)
for item in cmd.Execute() do
printfn "%A" item.ItemID
Is this even possible? Is my approach wrong? I could not find clear documentation on this use case but I thought it would be common enough it would be covered.
Update
Just to clarify what I am trying to achieve I am showing how I solve this in C#. In C# I create a DataSet object and populate it with the results of the Stored Procedure. From there I pick out the individual tables to work with. After extracting the tables I then use LINQ to transform the rows into the corresponding objects. It often looks something like the following:
using System.Data;
using System.Data.SqlClient;
var connStr = "**connection string**"
var sqlConnection = new SqlConnection(connStr );
var sqlCommand = new SqlCommand("ExampleProcedure", sqlConnection);
sqlCommand.CommandType = CommandType.StoredProcedure;
var dataSet = new DataSet();
var adapter = new SqlDataAdapter(sqlCommand);
adapter.Fill(dataSet);
var itemsTable = dataSet.Tables[0];
// Turn the itemsTable into a List<Item> using LINQ here
var customersTable = dataSet.Tables[1];
// Turn the customersTable into List<Customer> using LINQ here
I find this to be overly verbose for such a simple thing as extracting the individual tables but perhaps I am too sensitive to code clutter. I know that F# must have a more elegant and terse way to express this.
I don't know F#, however this is a data access problem.
When a stored procedure returns multiple resultsets, you need to access they in sequence, one by one.
cmd.ExecuteReader() returns an instance of a datareader pointing to the first resultset. You need to process this resultset, may be filling a list with instances of a custom class, than you call the method "NextResult" and you will have access to the next resultset and so on.
A reference for the method "NextResult": https://msdn.microsoft.com/pt-br/library/system.data.sqlclient.sqldatareader.nextresult(v=vs.110).aspx
I'm working on a winform application and I'm using a table named [File] in my SQL Server database.
I have a form that views some of "[File]" fields fID and fName in a combobox named SearchName. fID for Value and fName for Display.
SearchName Combobox is bound to dataset with dataadapter filling table with fID, fName, fPhoneNumber, fBalance, so I can use fName and fID.
I have also textboxes to add new "File" data like : fName, fAge, fNationality,fSex with a Save button with another combobox showing something called "Source".
When User clicks Save the data is saved to table [File] In DB and the adapter is filled again.
The dataset tableadapter was using a stored procedure as the following:
create proc [dbo].[ReadFileData](#fid int,#filter varchar(20))
as
begin
declare #f varchar(20)=#filter;
declare #id int =#fid;
if(#id=-1)
begin
if(#f='All')
select fID,fName,fPhoneNumbers,fBalance from [File]
else
if(#f='Blocked')
select fID,fName,fNotes,fBalance,fBlockDate,uFullName
from [File],[User] where fBlocked='True' and fBlocker=[uID]
order by fBlockDate desc
else
if(#f='nonBlocked')
select fID,fName,fPhoneNumbers,fBalance from [File] where fBlocked='False'
else
if(#f='notReady')
select fID,fName,fPhoneNumbers,fBalance from [File] where fAllTestsOK='False' and fBlocked='False'
else
if(#f='Ready')
select fID,fName,fPhoneNumbers,fBalance from [File] where fAllTestsOK='True' and fBlocked='False'
else
if(#f='NegBalanced')
select fID,fName,fPhoneNumbers,fBalance from [File] where fBalance<0
end
else
select f.fID,fName,fSex,fBirthDate,fPhoneNumbers,fAddress,fNationality,fNotes,fBalance,fBlocked,(select uFullName from [User] where uid=f.fBlocker) as fBlocker,
fLastEdited,(select uFullName from [User] where [uID]=f.fEditor) as fEditor, fBlockDate from [File] f where fID=#fid
end
It was taking too much time to save and fill the combobox again. I searched over the internet and I found out the problem is called "Patamter Sniffing/spoofing", because my procedure was selecting fields based on the values of the parameter it receives. I tried different ways to solve it, but nothing worked out for me. (P.S. I am using the same SP on other forms and data is filled immediately with no problems).
I deleted the whole dataset and created a new one with a new dataadapter using new Stored Procedure, this:
create proc [dbo].[GetAllFiles]
as
begin
select fID,fName,fPhoneNumbers,fBalance from [File]
end
Now first time the save and fill is done in no time, but after that it takes like 10+ seconds to fill.
I want to know what can I do to continue using the dataadapter to fill the combobox and solve time consuming problem?
If you have any suspicions that might cause these kind of problems, please let me know.
What other code parts or even design pictures can I provide to make my problem clearer?
Thanks to #Plutonix. He wrote it in a reply, just to make it clearer.
"You should spend a few hours on MSDN. You do not need to requery/refill/rebuild a datatable when you add rows; they can be refreshed. – Plutonix"
I used DataAdapterName.Adapter.Update(DatasetName) in save button and other update places. And kept fill only in page load event.
This is a followup post to this post. I am writing an accounting system backed by an h2 database. The tree of accounts is stored in the ACCOUNTS table, with the PARENT_ID column storing the links in the tree.
To get the path to a given node in the tree, I have the following stored procedure:
public static Long[] getAncestorPKs(Long id)
whose job is to produce an array of integers, being the PARENT_ID values between the given node and the root of the tree. Let's imagine it is defined like this (because I have tried this and I get the same error):
public static Long[] getAncestorPKs(Long id)
{
return new Long[]{new Long(1), new Long(2), new Long(3)};
}
It is properly registered in the database and I can call it from within a SQL query. My problem is that h2 seems to be unable to deal with the return value: if I use it like this:
SELECT ID FROM ACCOUNTS WHERE ID IN (ANCESTOR_PKS(5))
then I get the following error:
Data conversion error converting "(1, 2, 3)"; SQL statement:
SELECT ID FROM ACCOUNTS WHERE ID IN (ANCESTOR_PKS(5)) [22018-167]
If, instead, I send the following to the database:
SELECT ID FROM ACCOUNTS WHERE ID IN (1, 2, 3)
I get back a result set with 3 rows, containing the three integers (exactly what I expect).
I really can't see what is the problem here! I am returning an array of Longs, which are to be used in comparing against a column which contains BIGINTS. Why is h2 refusing to convert this array? I have tried making the return value be Object[], because the h2 documentation is not entirely clear whether this is required on the return side as well as on the call side, but that makes no difference at all. I'm just banging my head against a brick wall here. This ain't rocket science! Surely someone has written similar code before?
Many thanks in advance, before I go mad!
If the method returns an array of objects, then for the database this is one value of data type ARRAY. And not a table with 3 rows. But of course you don't use the data type ARRAY in your table, you use INT or BIGINT. So your query is incorrect.
Either the method needs to return a ResultSet, or you need to convert the array value to a table. To do that, you could use the function TABLE(..) as follows:
select x from table(x bigint = getAncestorPKs(1));
So what you could do is:
drop table accounts;
create table accounts(id int);
insert into accounts values(1), (2), (10), (20);
drop alias getAncestorPKs;
create alias getAncestorPKs as 'Long[] getAncestorPKs(Long id) {
return new Long[]{new Long(1), new Long(2), new Long(3)};
}';
select * from accounts where id in
(select x from table(x bigint = getAncestorPKs(1)));
I am trying to use Dapper support my data access for my server app.
My server app has another application that drops records into my database at a rate of 400 per minute.
My app pulls them out in batches, processes them, and then deletes them from the database.
Since data continues to flow into the database while I am processing, I don't have a good way to say delete from myTable where allProcessed = true.
However, I do know the PK value of the rows to delete. So I want to do a delete from myTable where Id in #listToDelete
Problem is that if my server goes down for even 6 mintues, then I have over 2100 rows to delete.
Since Dapper takes my #listToDelete and turns each one into a parameter, my call to delete fails. (Causing my data purging to get even further behind.)
What is the best way to deal with this in Dapper?
NOTES:
I have looked at Tabled Valued Parameters but from what I can see, they are not very performant. This piece of my architecture is the bottle neck of my system and I need to be very very fast.
One option is to create a temp table on the server and then use the bulk load facility to upload all the IDs into that table at once. Then use a join, EXISTS or IN clause to delete only the records that you uploaded into your temp table.
Bulk loads are a well-optimized path in SQL Server and it should be very fast.
For example:
Execute the statement CREATE TABLE #RowsToDelete(ID INT PRIMARY KEY)
Use a bulk load to insert keys into #RowsToDelete
Execute DELETE FROM myTable where Id IN (SELECT ID FROM #RowsToDelete)
Execute DROP TABLE #RowsToDelte (the table will also be automatically dropped if you close the session)
(Assuming Dapper) code example:
conn.Open();
var columnName = "ID";
conn.Execute(string.Format("CREATE TABLE #{0}s({0} INT PRIMARY KEY)", columnName));
using (var bulkCopy = new SqlBulkCopy(conn))
{
bulkCopy.BatchSize = ids.Count;
bulkCopy.DestinationTableName = string.Format("#{0}s", columnName);
var table = new DataTable();
table.Columns.Add(columnName, typeof (int));
bulkCopy.ColumnMappings.Add(columnName, columnName);
foreach (var id in ids)
{
table.Rows.Add(id);
}
bulkCopy.WriteToServer(table);
}
//or do other things with your table instead of deleting here
conn.Execute(string.Format(#"DELETE FROM myTable where Id IN
(SELECT {0} FROM #{0}s", columnName));
conn.Execute(string.Format("DROP TABLE #{0}s", columnName));
To get this code working, I went dark side.
Since Dapper makes my list into parameters. And SQL Server can't handle a lot of parameters. (I have never needed even double digit parameters before). I had to go with Dynamic SQL.
So here was my solution:
string listOfIdsJoined = "("+String.Join(",", listOfIds.ToArray())+")";
connection.Execute("delete from myTable where Id in " + listOfIdsJoined);
Before everyone grabs the their torches and pitchforks, let me explain.
This code runs on a server whose only input is a data feed from a Mainframe system.
The list I am dynamically creating is a list of longs/bigints.
The longs/bigints are from an Identity column.
I know constructing dynamic SQL is bad juju, but in this case, I just can't see how it leads to a security risk.
Dapper request the List of object having parameter as a property so in above case a list of object having Id as property will work.
connection.Execute("delete from myTable where Id in (#Id)", listOfIds.AsEnumerable().Select(i=> new { Id = i }).ToList());
This will work.