Using Variables In SQL Queries
May 18, 2009
I am a beginner when it comes to VB express. I went to the FAQ and found what looked like the answer to my question in "Database - How can I put the value of a variable/control into my SQL statement?" which said I should use thecode ...... where Field = ' " & variablename & " ' at the end of the SQL statement
I am using a field defined as a nchar with 10 charecters and my variable is defined as a string. my field has been given the value "abcdefghij" so it is full to avoid confusion with spaces and even though the variable is identical and I have used the len command to check there are no hidden spaces etc. When I run the query I get no records selected. What am I doing wrong?. If I use Where Field = 'abcdefghij', ie specify the value in the SQL I get the correct records selected but this does not give me the flexibility I need
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Feb 12, 2011
I'm in the middle of a project, I've got the bulk of it working but I cannot work out how to get my variables to modify the SQL query properly, I'll try and explain. GUI has 5 search fields Q1, Q2, Q3, Q4 & Q5 with 4 checkboxes that denote AND / OR operators that need to be inserted into the query correctly. If they are all set to 'AND' it works fine. However if the user wants 'Q1 AND Q2 OR Q3' then it fails. If I hard code then I just user brackets ie '(Q1 AND Q2) Or Q3'. For some reason I seam incapable of working out the code to achieve this...
Code snippet:
'Check AND OR Checkbox and assign Operator
If Q1AND.Checked = True Then
Q1Op = "AND"
Else : Q1Op = "OR"
[Code] .....
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Sep 20, 2011
I am using Visual Basic 2008 / MYSQL
Basically i have 2 tables in mysql called Data and products
The first sql query i want to do is something like this to scroll through the recordset of products and bring back information;
dbquery.commandtext = "select quantity, sku, condition from products"
But then what i want to do is bring back information from the Data table based on the sku and condition of the first sql?
so it would be something like this
subquery.commandtext = "select lowestprice from data where sku = *SKU FROM FIRST TABLE* and condition = *CONDITIONFROM FIRST TABLE*"
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Jan 6, 2010
I am writing a message system on my server, the xml is something like this
<xml>
<entry>
<sender>[code]....
my problem now i guess is 2 fold, i wish to combine the first 3 queries into a single query and place in a list or a collection or is there a way to do this with a single query that will give me my desired result?
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Dec 11, 2011
Last year (2010) I came across a FANTASTIC command that allowed me to take a string of variables with a common delimiter and break it all back out into separate variables (possibly an array) with one statement.
[Code]...
As long as the delimiter was a unique specifiable character, this one-statement command could break it out into elements. my memory and point me in the right direction.
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Sep 27, 2010
I have code, shown below, that works all except for 1 thing: The variables being passed byRef get passed, but once modified in the else section of the "if me.invokerequired" code of RecordData, the variables are never updated in the calling function. To reiterate, the calling function does not receive the updated data that is in the variables custid and amt.When debugging, I see the data change in the else section of "if me.invokerequired", but once it returns from the callback the data is missing.[code]
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Mar 23, 2012
I define some global variables of a class as follows:
Private Class MyClass
Private var1 as Decimal
Private list1 as List(Of string)[code].....
But I found that after this form is closed, all above variables, var1, list1, list2 still exist in memory. I thought they should be collected by gc since the form is already disposed as I confirmed.
Add: I have monitored half an hour after the form is closed. But these variables are not collected by gc. I have an automatic update procedure on the form which uses above variables.Since the above variables still hold values, the automatic update procedure is always called which causes exception. (One quick fix is to check if form.isDisposed in update procedure. But I do not think this is elegeant. Besides, these variables occupy memory.)
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Jan 7, 2010
Does the memory used in declaring variables are reclaimed by the OS when these variables go out of scope?Does the memory used be released by setting thier value to nothing? if not, then how can I force the garbage collector to run or excecute at a certain/desired time..How about in Windows Forms..How can we make sure that the memory used in initializing and showing forms be released if those forms were closed?
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Mar 8, 2011
Question 1: What is the difference between "Background Worker" and "Worker Pool" as indicated within the MSDN samples provided.
Question 2: I noticed while using, AddressOf _Function_, variables cannot be passed; what would be an efficient solution to this?
Question 3: While using multithreading is it required to invoke before setting variables, or only form properties?
Question 4: While using System.Net.Sockets is it safe/efficient to use Application.DoEvents while waiting for new data; or would be using a Do While loop be fine without DoEvents since the action would be multithreaded? Note: there can be up to 2000-3000 sockets in use at a time.
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Jun 9, 2012
I'm new in .NET programming.I have a class Form1 that includes Button1_Click event.Button1_Click creates a multiple Text Boxies at run time)Here is the class:
Public Class Form1
Dim shiftDown As Integer
Dim counter As Integer
[code].....
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Dec 5, 2010
I have a Access 2003 backend db and I'm using vb 2005 to connect to the db via conntection string. It works ok! I can see all the tables but only some of the queries. Why should some queries be absent? In 1 query I have a user define function which cuts up a string. I've created a new VB project with a new connection but the same result. I've compacted the database with not change.
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Jun 8, 2011
I am trying to UNION the two queries below without success.
Dim
ds1
As
New
DataSet
Dim
MyConnection1 As
New
OleDb.OleDbConnection(GetPOWERConnectionString())
[Code] .....
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Aug 3, 2011
I am trying to perform a search query using drop down boxes with a button named search. I want it to bring up the data that is searched for. I dont know where to start from, i have looked around for some coding and different ways to do it but they seem complicated, this is the bit of ASP that is my weakness, need some assistance and guidance. below is the code for the page;
<%@ Page Language="VB" MasterPageFile="~/MasterPage.master" AutoEventWireup="false" CodeFile="ForSale.aspx.vb" Inherits="Users_ForSale" title="Properties For Sale" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
[code]......
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Feb 19, 2010
I'm trying to figure out how to do SQL queries towards an SQL 2005 Express server and format the return value to JSON. I got the queries working using this (perhaps very newbie-like) code;
Imports System
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.UI
[code]....
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Aug 6, 2009
Where can I find informations on which WMI queries are in fact available for .NET interface through ManagementObjectSearcher. The command below returns exception for "Win32_LogicalDisk", but works for "Win32_Environment". Every reference in msdn directs to msdn library, which contains all Win32 and COM development classes (that seems not to be available from vb .net code):
[Code]...
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Nov 5, 2010
I have a form that will have at least 3 seperate sql queries that I want to have submitted with an onclick event.
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May 18, 2012
I've been going through a lot of forums and see a lot of mention of ADO.NET and how it's better to use. I guess because it's newer and being maintained with current times?I've done google searches for this, but every time I see different programming languages other than VB.NET implementing param queries with ADO.net, or it brings me to results that have oledb commands again.Is there a good ADO.NET for VB.NET tutorial with parametrized queries?
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Dec 14, 2011
finish my querie, it works for the first 2 rows, I need ti to loop through my dgv:
[Code]...
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Sep 22, 2010
I want to send the a vb.net application which will run some updates on the database. I have built the sql script files which i would normally run thru query analyser but that is not available thru MSDE.I know i can use OSQL or ISQL to run these scripts but i really want to run them thru a VB.Net application.here is the code i'm using which is generating an error beacuse i'm trying to execute more than one statement?
Dim connectionString As String = ' CONNECTION STRING IS HERE
Dim conn As New SqlClient.SqlConnection(connectionString)
Dim cmd As New SqlClient.SqlCommand
[code]....
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Nov 23, 2009
i have a form which once the user has entered their correct Account No they will access the jobs relating to their number. I now need to use and update query so that once I select yes in the Query handled box, after clicking the update button, this row will then be deleted from the table. Here is the code that I have so far:
Public Class Form1
Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click
End Sub
[code]....
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Aug 24, 2011
I have a basic grid of Linq2Sql entities (frmList). I have a separate form for editing (frmEdit). frmEdit has its own DataContext (as that appears to be the recommended way). How can I tell when my detail form has saved changes?
I don't see a built-in method. I am considering raising an event on the detail form when I save the datacontex, but not sure how I consume this event on frmList, and I have a feeling these events are already created for me somewhere?
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Aug 2, 2011
We have a reporting system where in we are getting unexpected results:
1) The size of reports at different time of interval is different?
2) The reports are writen as pdf to a directory. When we have thousand of older unused pdf(which will not get merged) in the directory the Adobe Life Cycle(to murge the PDF) throws error.But when we clear the directory by deleting the old unused pdf, it works fine?
3) Some of the pdf that are rejected by Adobe life cycle may or may not be corrupted. Meaning they may or may not open up with Adobe Reader, manually.
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May 6, 2010
I have a data driven application in <acronym title="Visual Basic">VB</acronym> which works with an SQL Server 05 Database.Since this app makes use of many queries and commands, occasionally i'me getting a timeout error as the connection pool is full. So i figured that at a specifc point in time within the app,i'll clear the connection pools using the ClearAllPools method rather than increase max pool size.
I'm using the performance monitor on my XP development machine (NumberOfPooledConnections) however not once do i see the number of Pooled Connections reset to 0 even when that method is called.How can I determine that my solution is working (if it is) before I deploy the update?
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Apr 15, 2012
always had a problem getting my head around it. I don't have a very strong mental model of how the code flows. My main problem is i think i understand the syntax, but not really its application. Any links people found useful would be great.
Couple of questions. The code below doesn't make sense to me (written by someone else) the application is basically a csv reader, but manipulates the data.
Public Sub entryType()
[code].....
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Apr 23, 2009
I am using C# and MSAccess as my database.
Code:private void ExecuteQuery(string strempname,string strQuestion,string IndividualRating,string OverallRating, string Comment1, string Comment2,string Comment3, string SessionName) { string strQuery= string.Empty; try { strQuery = "insert into FeedbackDetails(EmpName,Question,IndividualRating,OverallRating,Comment1,Comment2,Comment3,SessionName)"
[code]....
so this actually opens and close connection for every method. but i need to open and close the connection only one time. so how to customize this code to achieve my need. now i am hitting database for 14 times in a button click as of now. instead i need to hit only once but all the rows has to be inserted in my database.i am using MSAccess as Database.
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Dec 4, 2009
Using parameterized queries with ms access 2003 integration. To search any data according to different criteria.
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Oct 11, 2010
Let's say I have 3 tables: carts, baskets and eggs where a basket can contain many eggs and where carts contain many baskets. Each basket has a foreign key that maps to a cart and each egg has a foreign key that maps to a basket.I need to return a table that contains these 3 columns:Cart Name | Count of Baskets in Cart | Count of Eggs in Cart.Each table is an EF and I'm using linq with VB.So far, I have 2 queries: one that returns the columns Cart Name and Count of Basket and another one that returns Cart Name and Count of Eggs. How can I combine these two result tables so that I get the results in one table?
Dim query1 = (From cart In myEntities.Carts
Where cart.UserID = TheUserID
Join baskets In myEntities.Baskets On baskets.CartID Equals cart.CartID
[code]...
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Jan 6, 2012
I have an application that works together with a SQL database. This database has more than 40 tables and my applican has to extract different situations from those tables.
I have predefined some queries for the situations that I know they need to be in the application.
The idea is that I need kind of a module in which an user can create his own situation based on the tables, views, functions and procedures that already exist in the database. Something like it is in SQL. There has to be a library or something which will read my sql database directly from my application and which allow the user to create his own queries and situations.
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May 18, 2012
I'm making two queries[code]...
How can I merge those two queries to have only one I can use as DataSource.
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Dec 5, 2009
How to use parameterized queries in vb.net? Because I always wanted to make a program that could read an ms access database and display results based on your query.
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