My Goal: Add a column to mysql database using visual basic!
I have tried multiple ways, but here is the code I'm currently using:
Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click
MysqlConn = New MySqlConnection
MysqlConn.ConnectionString = "Server=xxx.xx.xxx.xxx;Port=3306;Database=test;Uid=tester;Pwd=***"
Try
MysqlConn.Open()
Dim Query As String
Query = "ALTER TABLE user ADD test INT NOT NULL"
COMMAND = New MySqlCommand(Query, MysqlConn)
MysqlConn.Close()
Catch ex As Exception
End Try
End Sub
I think it's a problem with the query! Thanks for your help in advance!
This is different from ms sql, it's visual basic.
My visual studio was actually not using my most up to date code and now everything is working LOL. Here is my revised code:
MysqlConn = New MySqlConnection
MysqlConn.ConnectionString = "Server=**.**.***.***;Port=3306;Database=test;Uid=tester;Pwd=***"
Dim READER As MySqlDataReader
Try
MysqlConn.Open()
Dim Query As String
Query = "alter table test.user add test int not null"
COMMAND = New MySqlCommand(Query, MysqlConn)
READER = COMMAND.ExecuteReader
MysqlConn.Close()
Catch ex As Exception
End Try
Related
The DataGridView won't show the PDF file from MySQL, it has red x mark on the table where the pdf. I want the file name displayed on the DataGridView. I really need help. Thanks alot. I'm using VB.Net and Workbench.
Private Sub Admin_Handouts_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Try
MysqlConn = New MySqlConnection
MysqlConn.ConnectionString = "server=; userid=; password=; database=cai"
MysqlConn.Open()
sql = "SELECT Code FROM cai.subjects"
command = New MySqlCommand(sql, MysqlConn)
da = New MySqlDataAdapter
dt = New DataTable
da.SelectCommand = command
da.Fill(dt)
dgvfiles.DataSource = dt
Catch ex As MySqlException
MsgBox(ex.Message)
Finally
MysqlConn.Close()
da.Dispose()
End Try
End Sub
If you have the iTextSharp library you can read the document properties from the PDF when you load it as an object.
I don't know if the file would retain the filename property when you add it to the table, though.
https://github.com/itext/itext7-dotnet
I already read all the questions and answers from previous post
but not fit with my problem
Problem :
I want to display data from db(mysql) to datagrid
but the problem is MySqlDataReader doesnt recognize
SelectCommand
Fill
Update
as the member of MySqlDataReader
I follow the exact same way of code writing from the tutorial
Why this problem occur ??
Below I attached my code.
I hope someone could help me.
Imports MySql.Data.MySqlClient
Public Class AdminAddItem
Dim MysqlConnection As MySqlConnection
Dim FoodCommand As MySqlCommand
Dim DataFoodRead As MySqlDataReader
Dim dbDataSetFood As New DataTable
Private Sub btnLoadFood_Click(sender As Object, e As EventArgs) Handles btnLoadFood.Click
'declare new connection
MysqlConnection = New MySqlConnection
'prepare connection string
MysqlConnection.ConnectionString =
"server = localhost; userid = root; password = 1234 ; database = kedaikopimamba_db"
Dim bSource As New BindingSource
Try
MysqlConnection.Open()
Dim query As String
query = "select * from kedaikopimamba_db.foodtable"
FoodCommand.Connection = MysqlConnection
FoodCommand.CommandText = query
DataFoodRead.SelectCommand = FoodCommand
DataFoodRead.Fill(dbDataSetFood)
bSource.DataSource = dbDataSetFood
dgDisplayItem.DataSource = bSource
DataFoodRead.Update(dbDataSetFood)
MysqlConnection.Close()
Catch ex As MySqlException
MessageBox.Show(ex.Message)
Finally
MysqlConnection.Dispose()
End Try
End Sub
End Class
What part to your code is the error? Please let us know to easily identify the problem.
I have the following functional code:
Call ConnSettings()
Dim objDs As New DataSet
Dim Query As String
Query = "the query"
Cmd = New MySqlCommand(Query, MysqlConn)
Dim dAdapter As New MySqlDataAdapter
dAdapter.SelectCommand = Cmd
''Dim dAdapter As New MySqlDataAdapter(Query, MysqlConn)
Try
MysqlConn.Open()
dAdapter.Fill(objDs)
MysqlConn.Close()
Catch ex As Exception
MessageBox.Show(ex.Message)
Finally
MysqlConn.Dispose()
End Try
I have noticed that the code is equally functional if I also use
Dim dAdapter As New MySqlDataAdapter(Query, MysqlConn)
instead of:
Cmd = New MySqlCommand(Query, MysqlConn)
Dim dAdapter As New MySqlDataAdapter
dAdapter.SelectCommand = Cmd
Obviously, I would like to use a single line instead of three. However, I am fairly new to VB and would like to know if there are any issues with doing that.
Let's try to improve your code....
First ConnSettings doesn't initialize a global connection variable but a local one and returns it
Public Function ConnSettings() As MySqlConnection
Dim conn As MySqlConnection
conn = new MySqlConnection(yourConnectionStringHere)
conn.Open()
return conn
End Function
Now the code that needs a MySqlConnection could call this ConnSettings and put the return value in a Using Statement
objDS = new DataSet()
Try
Using conn = ConnSettings()
Using dAdapter = New MySqlDataAdapter(theQuery, conn)
dAdapter.Fill(objDs)
End Using
End Using
Catch(ex as Exception
MessageBox.Show(ex.Message)
End Try
This code puts the connection returned in a Using Statement. When the code flows out of the Using Statement the connection is closed and disposed (same for the MySqlDataAdapter) As you can see there is no need for the Finally clause and the Try/Catch block is present just because you want to give an error message to your user (while this is a common practice there is no really sense to put your user in the unconfortable position to try to understand these technically dense messages, better use a log file and advise your user to send the log to you)
In this context also the code inside the ConnSettings is a bit useless. What you really need is just the connectionstring and you could write the creation of the MySqlConnection directly in the calling code.
I am currently working on connecting my data grid view to my database, but the problem is I can't connect with this error : MySql.Data.MySqlClient.MySqlCommand' cannot be converted to 'System.Data.SqlClient.SqlCommand
here's my code:
Private Sub populateGird()
Dim da As New SqlDataAdapter
Dim ds As New DataSet
Dim bs As New BindingSource
Try
sqlC = New MySqlCommand("SELECT c_id, CONCAT(c_firstname, c_lastname), rank_name, c_bir_status, rank_basic_pay, rank_positional_allowance," &
"rank_meal_allowance, ca_worth FROM tbl_crew, tbl_cash_advance, tbl_rank", conn)
da.SelectCommand = sqlC '--> error is that sqlC
da.Fill(ds)
bs.DataSource = ds
PayrollGrid.DataSource = bs
da.Update(ds)
conn.Close()
Catch ex As Exception
MessageBox.Show(ex.Message)
Finally
conn.Dispose()
End Try
this is my connection code in a module:
Imports MySql.Data.MySqlClient
Module Module1
Public conn As MySqlConnection
Public Sub connect()
conn = New MySqlConnection
conn.ConnectionString = "server=localhost;user=root;database=fat2x_payroll;pwd=;Convert Zero Datetime=True"
Try
conn.Open()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
End Module
The error message is quite clear - you are trying to assign from an incompatible type! SelectCommand is of type System.Data.SqlClient.SqlCommand because you have defined da as a variable of type System.Data.SqlClient.SqlDataAdapter. On the other hand, you are creating a variable of type MySql.Data.MySqlClient.MySqlCommand, which is a different type and which cannot be converted to SqlCommand when you try to do the assignment.
The way to fix this is to change your code to use the corresponding classes from MySql.Data.MySqlClient, like so:
Dim da As New MySqlDataAdapter
Change your declaration of the SqlDataAdapter to the appropriate type for MySQL (I'm guessing MySqlDataAdapter?)
Dim da As New SqlDataAdapter
I Have a form and I like to retrieve all the columns in MySql database and display it using comboBox in vbNET.
I dont know how to query that.
Heres my sample codes:
conn = New MySqlConnection
conn.ConnectionString = "server=localhost; userid=root; password=root; database=dbase"
Dim da As New MySqlDataAdapter
Dim dt As New DataTable
Dim bs As New BindingSource
Dim ds As New DataSet
Try
ds.Clear()
conn.Open()
cmd = New MySqlCommand("[watt??]")
da = New MySqlDataAdapter(cmd)
da.SelectCommand.Connection = conn
da.Fill(ds, "gradelvl")
cbGradeLvl.Text = ds.Tables(0).Rows(0).Item(0)
Catch ex As MySqlException
MsgBox(ex.Message)
Finally
conn.Close()
End Try
I wish to reopen the question because the suggested duplicate link while correct is incomplete in reference to the VB.NET tag.
You could extract informations about your table columns also using the GetSchema method of your connection....
For example
Using cnn = new MySqlConnection(.....)
cnn.Open()
Dim dt = cnn.GetSchema("Columns", new string () {Nothing, Nothing, "gradelvl"})
for each row in dt.Rows
cbGradeLvl.Items.Add(row("COLUMN_NAME").ToString)
Next
End Using
You can get an understanding of the inner working of GetSchema looking at the MSDN docs on the SqlConnection page. I don't know if the MySql Connector supports all the options or more, but that could be a starting point for other searches