我试图在 vb.net 的文本框中显示我从 COUNT(*) 查询中获得的值，但不是显示获得的值，而是显示实际查询。
这是我的代码:
Imports MySql.Data.MySqlClient
Public Class Statistics
Dim conn As MySqlConnection
Dim command As MySqlCommand
Dim query As String
Dim dadapter As New MySqlDataAdapter
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
conn = New MySqlConnection
conn.ConnectionString =
"server=localhost;userid=root;database=librarydatabase"
Dim reader As MySqlDataReader
Try
conn.Open()
query = "SELECT COUNT(*) FROM login where users='" & Username.Text & "'"
command = New MySqlCommand(query, conn)
reader = command.ExecuteReader
dadapter.SelectCommand = command
If reader.HasRows Then
reader.Read()
takenout.Text = (query)
End If
conn.Close()
Catch ex As MySqlException
MessageBox.Show(ex.Message)
Finally
conn.Dispose()
End Try
End Sub
这是我的程序的屏幕截图:
当尝试修复代码时，我将其更改为将 takenout.Text = (query) 替换为 takenout.Text = (reader.read()) 并删除上面的 reader.read()) 和 dadapter.SelectCommand = command
这里是修改后的代码:
Imports MySql.Data.MySqlClient
Public Class Statistics
Dim conn As MySqlConnection
Dim command As MySqlCommand
Dim query As String
Dim dadapter As New MySqlDataAdapter
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
conn = New MySqlConnection
conn.ConnectionString =
"server=localhost;userid=root;database=librarydatabase"
Dim reader As MySqlDataReader
Try
conn.Open()
query = "SELECT COUNT(*) FROM login where users='" & Username.Text & "'"
command = New MySqlCommand(query, conn)
reader = command.ExecuteReader
If reader.HasRows() Then
takenout.Text = (reader.Read())
End If
conn.Close()
Catch ex As MySqlException
MessageBox.Show(ex.Message)
Finally
conn.Dispose()
End Try
End Sub
此代码没有解决问题，而是在按下按钮时无论用户名文本框中的内容如何，都会在文本框中显示 true。
这是一张图片:
最佳答案
改用 command.ExecuteScalar()。
关于mysql - 将从 mysql 查询获得的值显示到 VB.net 文本框中，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41161371/