如何在使用 vb.net 插入新数据之前检查现有数据？
How to check existing data before inserting a new data using vb.net?
我有一个 table，它是 external_work_duty_details。所以我想检查用户何时无法插入与现有数据相同的数据。我不知道如何编写代码
例如：A 想在 24/5/2022 申请到 25/5/2022 但 A 已经在同一天申请了。所以这里当A点击按钮提交时，会出现显示消息说A不能申请。 A 只有在现有数据被拒绝或取消时才能应用它，但如果它正在等待或批准 A 则不能应用。
列确认用于状态。默认 0 = 未决。 1 = 已批准，2 = 已拒绝，3 = 已取消。
external_work_duty_details Table
id duty_id employee_no UserId employee_dept Reason Start_date End_date Remarks Acknowledgement
48 D2205-00029 1315 800 3 OUTSTATION 2022-05-17 2022-05-19 out test 3
49 D2205-00030 1511 1342 32 COMPANY TRIP 2022-05-23 2022-05-27 trip test 1
50 D2205-00031 1115 127 3 MEETING 2022-05-25 2022-05-25 meet 1
这是我的 vb.net 代码（编辑代码）
Private Function checkExistingData(ByVal startdate As String, ByVal enddate As String, ByVal intUserid As Integer, ByVal reason As String) As DataTable
Dim dt As New DataTable
Dim strCheck As String = "SELECT * FROM FROM exteral_work_duty_details WHERE Start_Date=@Start_Date, End_Date=@End_Date, UserId=@UserId, Reason=@Reason"
myconn.AddParameter("@Start_Date", MySqlDbType.VarChar)
myconn.SetParameter("@Start_Date", startdate)
myconn.AddParameter("@End_Date", MySqlDbType.VarChar)
myconn.SetParameter("@End_Date", enddate)
myconn.AddParameter("@UserId", MySqlDbType.Int32)
myconn.SetParameter("@UserId", intUserid)
myconn.AddParameter("@Reason", MySqlDbType.String)
myconn.SetParameter("@Reason", reason)
Try
myconn.OpenConnection()
myconn.FillDataTable(dt, strCheck)
myconn.CloseConnection()
myconn.ClearAllParameter()
Catch ex As Exception
myconn.CloseConnection()
myconn.ClearAllParameter()
End Try
Return dt
End Function
使用 VB.NET 6.0.5、Visual Studio 2022 社区和 Windows 10 x64。
我用这个 SQL 在 XAMPP 本地主机上创建了 MySQL 数据库：
-- phpMyAdmin SQL Dump
-- version 5.1.3
-- https://www.phpmyadmin.net/
--
-- Host: 127.0.0.1
-- Generation Time: May 25, 2022 at 01:06 PM
-- Server version: 8.0.29
-- PHP Version: 8.0.18
SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
START TRANSACTION;
SET time_zone = "+00:00";
--
-- Database: `company`
--
-- --------------------------------------------------------
--
-- Table structure for table `external_work_duty_details`
--
CREATE TABLE `external_work_duty_details` (
`id` int NOT NULL,
`duty_id` varchar(255) COLLATE utf8mb4_general_ci NOT NULL,
`employee_no` int NOT NULL,
`UserId` int NOT NULL,
`employee_dept` int NOT NULL,
`Reason` varchar(255) COLLATE utf8mb4_general_ci NOT NULL,
`Start_date` date DEFAULT NULL,
`End_date` date DEFAULT NULL,
`Remarks` varchar(255) COLLATE utf8mb4_general_ci NOT NULL,
`Acknowledgement` int NOT NULL DEFAULT '1'
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;
--
-- Indexes for dumped tables
--
--
-- Indexes for table `external_work_duty_details`
--
ALTER TABLE `external_work_duty_details`
ADD PRIMARY KEY (`id`);
--
-- AUTO_INCREMENT for dumped tables
--
--
-- AUTO_INCREMENT for table `external_work_duty_details`
--
ALTER TABLE `external_work_duty_details`
MODIFY `id` int NOT NULL AUTO_INCREMENT;
COMMIT;
然后我使用了这段代码并进行了测试，它可以正常工作。请随意调整以满足您的需求。
Imports MySqlConnector
' Don't forget to install MySqlConnector from NuGet Package Manger ✽
Public Class Form1
Private Sub Button1_Click_1(sender As Object, e As EventArgs) Handles Button1.Click
Dim conn As New MySqlConnection
Dim cmd As New MySqlCommand
Dim UserID As String = TextBoxUserID.Text
Dim Start_Date = DateTimePicker_Start.Value.ToString("yyyy-M-d")
Dim End_Date = DateTimePicker_End.Value.ToString("yyyy-M-d")
Dim Reason As String = TextBoxReason.Text
Dim Remarks As String = TextBoxRemarks.Text
conn.ConnectionString = "Server=localhost;Database=company;Uid=root;Pwd=;"
cmd.Connection = conn
Dim strCheck As String = "SELECT * FROM external_work_duty_details WHERE Start_Date=@Start_Date AND End_Date=@End_Date AND UserId=@UserId AND Reason=@Reason AND (Acknowledgement = 1 OR Acknowledgement = 2)"
' assuming that 1 is for pending and 2 for approved
' remember to set in your MySQL database default value for Acknowledgement = 1
If (conn.State = ConnectionState.Closed) Then
conn.Open()
End If
cmd.CommandText = strCheck
cmd.Parameters.AddWithValue("@UserID", UserID)
cmd.Parameters.AddWithValue("@Start_Date", Start_Date)
cmd.Parameters.AddWithValue("@End_Date", End_Date)
cmd.Parameters.AddWithValue("@Reason", Reason)
Dim dr = cmd.ExecuteReader()
If dr.HasRows = False Then
' here you can add code to save new request
' Users can add new request because their previous request was either rejected or canceled
' here routine to add new request
cmd.Parameters.Clear()
dr.Close()
Dim strInsert As String = "INSERT INTO external_work_duty_details (UserID, Start_Date, End_Date, Reason, Remarks) VALUES (@UserID, @Start_Date, @End_Date, @Reason, @Remarks)"
If (conn.State = ConnectionState.Closed) Then
conn.Open()
End If
cmd.CommandText = strInsert
cmd.Parameters.AddWithValue("@UserID", UserID)
cmd.Parameters.AddWithValue("@Start_Date", Start_Date)
cmd.Parameters.AddWithValue("@End_Date", End_Date)
cmd.Parameters.AddWithValue("@Reason", Reason)
cmd.Parameters.AddWithValue("@Remarks", Remarks)
Dim CommandStatus As Integer = cmd.ExecuteNonQuery()
If CommandStatus > 0 Then
MessageBox.Show("Request saved!")
Else
MessageBox.Show("Something went wrong!")
End If
Else
Dim dt = New DataTable()
Dim Result As String = ""
dt.Clear()
DataGridView1.DataSource = dt
DataGridView1.DataSource = Nothing
DataGridView1.Refresh()
dt.Load(dr)
DataGridView1.AutoGenerateColumns = True
DataGridView1.DataSource = dt
DataGridView1.Refresh()
dr = cmd.ExecuteReader()
While dr.Read()
Select Case dr("Acknowledgement").ToString
Case 1
Result = "Pending"
Case 2
Result = "Approved"
End Select
MessageBox.Show("Your request: (" & dr("Reason").ToString & ") already saved and its (" & Result & ")!")
End While
End If
End Sub
End Class
- 我没有看到你所有的代码；所以请随意修改我的代码以满足您的需求。让我知道它是否有效以及您是否需要进一步的帮助
求助。
- 我不能保证它是最佳解决方案，但至少它就我的理解回答了你的问题。
您可以 download the project 并在实施之前对其进行测试。
✽ 要打开 NuGet 程序包管理器，请在不按住 Alt 键的情况下连续按下以下四个键。
AltTNN
我终于有了解决方案
我使用这个 sql 代码并将其写入存储过程
DELIMITER $$
USE `lrtapp`$$
DROP PROCEDURE IF EXISTS `SP_EXTERNAL_WORK_DUTY_DETAILS_SELECT_EXISTING_DATA`$$
CREATE DEFINER=`leaderr1`@`%` PROCEDURE `SP_EXTERNAL_WORK_DUTY_DETAILS_SELECT_EXISTING_DATA`(
IN _user_id INT,
IN _start_date VARCHAR (10),
IN _end_date VARCHAR (10)
)
BEGIN
SELECT UserId , duty_id FROM external_work_duty_details WHERE UserId=_user_id AND (Start_Date BETWEEN _start_date AND _end_date OR End_Date BETWEEN _start_date AND _end_date) AND (acknowledgement = 0 OR acknowledgement = 1)
;
END$$
DELIMITER ;
它对我有用。然后我在我的 vb.net 代码中这样调用它
Public Function GetExistingdata(ByVal intuserId As Integer, ByVal startDate As String, ByVal enddate As String) As DataTable
Dim result As DataTable = Nothing
Try
result = New DataTable
'Initialize the connection and transation
If Not Me._IsInit Then
Me.Init()
Me._IsCommitHere = True
End If
Using command As New MySqlCommand("SP_EXTERNAL_WORK_DUTY_DETAILS_SELECT_EXISTING_DATA", Me._SQLConn, Me._SQLTran)
Dim Param As New MySqlParameter
command.CommandType = CommandType.StoredProcedure
Param = New MySqlParameter
Param.ParameterName = "@_user_id"
Param.MySqlDbType = MySqlDbType.Int32
Param.Direction = ParameterDirection.Input
Param.Value = clsCommon.ToInt(intuserId)
command.Parameters.Add(Param)
Param = New MySqlParameter
Param.ParameterName = "@_start_date"
Param.MySqlDbType = MySqlDbType.VarChar
Param.Direction = ParameterDirection.Input
Param.Value = clsCommon.ToStr(startDate)
command.Parameters.Add(Param)
Param = New MySqlParameter
Param.ParameterName = "@_end_date"
Param.MySqlDbType = MySqlDbType.VarChar
Param.Direction = ParameterDirection.Input
Param.Value = clsCommon.ToStr(enddate)
command.Parameters.Add(Param)
Dim SQLReader As MySqlDataReader = command.ExecuteReader
result.Load(SQLReader)
SQLReader.Close()
SQLReader = Nothing
End Using
Catch ex As MySqlException
'Dim str_funcs As String = Me.ToString
'clsErrorLog.ErrorLog(Me.fstrPageID, ex)
End Try
Return result
End Function
还有这个
Private Function CheckExistingData(ByVal intUserId As Integer, ByVal strtDate As String, ByVal endDate As String) As DataTable
Using checking As New clsExternalWorkDuty_func
Dim dt As New DataTable
dt = checking.GetExistingdata(intUserId, strtDate, endDate)
Return dt
End Using
End Function
然后我像这样在 ErrorFree() 函数中调用 CheckExistingData() 函数
Private Function ErrorFree() As Boolean
Dim check As New DataTable
check = CheckExistingData(lblhdddnuserid.Text, datepickerFrom.Text, datepickerto.Text)
If check.Rows.Count > 0 Then
DisplayMessage("Error", "Error", "Something went wrong, the data already exist. Please check and change the data.")
Return False
Exit Function
End If
Return True
End Function
最后，我在 btnSubmitExternalWorkDutyDetails_Click()
中调用了 ErrorFree() 函数
我有一个 table，它是 external_work_duty_details。所以我想检查用户何时无法插入与现有数据相同的数据。我不知道如何编写代码
例如：A 想在 24/5/2022 申请到 25/5/2022 但 A 已经在同一天申请了。所以这里当A点击按钮提交时，会出现显示消息说A不能申请。 A 只有在现有数据被拒绝或取消时才能应用它，但如果它正在等待或批准 A 则不能应用。 列确认用于状态。默认 0 = 未决。 1 = 已批准，2 = 已拒绝，3 = 已取消。
external_work_duty_details Table
id duty_id employee_no UserId employee_dept Reason Start_date End_date Remarks Acknowledgement
48 D2205-00029 1315 800 3 OUTSTATION 2022-05-17 2022-05-19 out test 3
49 D2205-00030 1511 1342 32 COMPANY TRIP 2022-05-23 2022-05-27 trip test 1
50 D2205-00031 1115 127 3 MEETING 2022-05-25 2022-05-25 meet 1
这是我的 vb.net 代码（编辑代码）
Private Function checkExistingData(ByVal startdate As String, ByVal enddate As String, ByVal intUserid As Integer, ByVal reason As String) As DataTable
Dim dt As New DataTable
Dim strCheck As String = "SELECT * FROM FROM exteral_work_duty_details WHERE Start_Date=@Start_Date, End_Date=@End_Date, UserId=@UserId, Reason=@Reason"
myconn.AddParameter("@Start_Date", MySqlDbType.VarChar)
myconn.SetParameter("@Start_Date", startdate)
myconn.AddParameter("@End_Date", MySqlDbType.VarChar)
myconn.SetParameter("@End_Date", enddate)
myconn.AddParameter("@UserId", MySqlDbType.Int32)
myconn.SetParameter("@UserId", intUserid)
myconn.AddParameter("@Reason", MySqlDbType.String)
myconn.SetParameter("@Reason", reason)
Try
myconn.OpenConnection()
myconn.FillDataTable(dt, strCheck)
myconn.CloseConnection()
myconn.ClearAllParameter()
Catch ex As Exception
myconn.CloseConnection()
myconn.ClearAllParameter()
End Try
Return dt
End Function
使用 VB.NET 6.0.5、Visual Studio 2022 社区和 Windows 10 x64。
我用这个 SQL 在 XAMPP 本地主机上创建了 MySQL 数据库：
-- phpMyAdmin SQL Dump
-- version 5.1.3
-- https://www.phpmyadmin.net/
--
-- Host: 127.0.0.1
-- Generation Time: May 25, 2022 at 01:06 PM
-- Server version: 8.0.29
-- PHP Version: 8.0.18
SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
START TRANSACTION;
SET time_zone = "+00:00";
--
-- Database: `company`
--
-- --------------------------------------------------------
--
-- Table structure for table `external_work_duty_details`
--
CREATE TABLE `external_work_duty_details` (
`id` int NOT NULL,
`duty_id` varchar(255) COLLATE utf8mb4_general_ci NOT NULL,
`employee_no` int NOT NULL,
`UserId` int NOT NULL,
`employee_dept` int NOT NULL,
`Reason` varchar(255) COLLATE utf8mb4_general_ci NOT NULL,
`Start_date` date DEFAULT NULL,
`End_date` date DEFAULT NULL,
`Remarks` varchar(255) COLLATE utf8mb4_general_ci NOT NULL,
`Acknowledgement` int NOT NULL DEFAULT '1'
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;
--
-- Indexes for dumped tables
--
--
-- Indexes for table `external_work_duty_details`
--
ALTER TABLE `external_work_duty_details`
ADD PRIMARY KEY (`id`);
--
-- AUTO_INCREMENT for dumped tables
--
--
-- AUTO_INCREMENT for table `external_work_duty_details`
--
ALTER TABLE `external_work_duty_details`
MODIFY `id` int NOT NULL AUTO_INCREMENT;
COMMIT;
然后我使用了这段代码并进行了测试，它可以正常工作。请随意调整以满足您的需求。
Imports MySqlConnector
' Don't forget to install MySqlConnector from NuGet Package Manger ✽
Public Class Form1
Private Sub Button1_Click_1(sender As Object, e As EventArgs) Handles Button1.Click
Dim conn As New MySqlConnection
Dim cmd As New MySqlCommand
Dim UserID As String = TextBoxUserID.Text
Dim Start_Date = DateTimePicker_Start.Value.ToString("yyyy-M-d")
Dim End_Date = DateTimePicker_End.Value.ToString("yyyy-M-d")
Dim Reason As String = TextBoxReason.Text
Dim Remarks As String = TextBoxRemarks.Text
conn.ConnectionString = "Server=localhost;Database=company;Uid=root;Pwd=;"
cmd.Connection = conn
Dim strCheck As String = "SELECT * FROM external_work_duty_details WHERE Start_Date=@Start_Date AND End_Date=@End_Date AND UserId=@UserId AND Reason=@Reason AND (Acknowledgement = 1 OR Acknowledgement = 2)"
' assuming that 1 is for pending and 2 for approved
' remember to set in your MySQL database default value for Acknowledgement = 1
If (conn.State = ConnectionState.Closed) Then
conn.Open()
End If
cmd.CommandText = strCheck
cmd.Parameters.AddWithValue("@UserID", UserID)
cmd.Parameters.AddWithValue("@Start_Date", Start_Date)
cmd.Parameters.AddWithValue("@End_Date", End_Date)
cmd.Parameters.AddWithValue("@Reason", Reason)
Dim dr = cmd.ExecuteReader()
If dr.HasRows = False Then
' here you can add code to save new request
' Users can add new request because their previous request was either rejected or canceled
' here routine to add new request
cmd.Parameters.Clear()
dr.Close()
Dim strInsert As String = "INSERT INTO external_work_duty_details (UserID, Start_Date, End_Date, Reason, Remarks) VALUES (@UserID, @Start_Date, @End_Date, @Reason, @Remarks)"
If (conn.State = ConnectionState.Closed) Then
conn.Open()
End If
cmd.CommandText = strInsert
cmd.Parameters.AddWithValue("@UserID", UserID)
cmd.Parameters.AddWithValue("@Start_Date", Start_Date)
cmd.Parameters.AddWithValue("@End_Date", End_Date)
cmd.Parameters.AddWithValue("@Reason", Reason)
cmd.Parameters.AddWithValue("@Remarks", Remarks)
Dim CommandStatus As Integer = cmd.ExecuteNonQuery()
If CommandStatus > 0 Then
MessageBox.Show("Request saved!")
Else
MessageBox.Show("Something went wrong!")
End If
Else
Dim dt = New DataTable()
Dim Result As String = ""
dt.Clear()
DataGridView1.DataSource = dt
DataGridView1.DataSource = Nothing
DataGridView1.Refresh()
dt.Load(dr)
DataGridView1.AutoGenerateColumns = True
DataGridView1.DataSource = dt
DataGridView1.Refresh()
dr = cmd.ExecuteReader()
While dr.Read()
Select Case dr("Acknowledgement").ToString
Case 1
Result = "Pending"
Case 2
Result = "Approved"
End Select
MessageBox.Show("Your request: (" & dr("Reason").ToString & ") already saved and its (" & Result & ")!")
End While
End If
End Sub
End Class
- 我没有看到你所有的代码；所以请随意修改我的代码以满足您的需求。让我知道它是否有效以及您是否需要进一步的帮助 求助。
- 我不能保证它是最佳解决方案，但至少它就我的理解回答了你的问题。
您可以 download the project 并在实施之前对其进行测试。
✽ 要打开 NuGet 程序包管理器，请在不按住 Alt 键的情况下连续按下以下四个键。
AltTNN
我终于有了解决方案
我使用这个 sql 代码并将其写入存储过程
DELIMITER $$
USE `lrtapp`$$
DROP PROCEDURE IF EXISTS `SP_EXTERNAL_WORK_DUTY_DETAILS_SELECT_EXISTING_DATA`$$
CREATE DEFINER=`leaderr1`@`%` PROCEDURE `SP_EXTERNAL_WORK_DUTY_DETAILS_SELECT_EXISTING_DATA`(
IN _user_id INT,
IN _start_date VARCHAR (10),
IN _end_date VARCHAR (10)
)
BEGIN
SELECT UserId , duty_id FROM external_work_duty_details WHERE UserId=_user_id AND (Start_Date BETWEEN _start_date AND _end_date OR End_Date BETWEEN _start_date AND _end_date) AND (acknowledgement = 0 OR acknowledgement = 1)
;
END$$
DELIMITER ;
它对我有用。然后我在我的 vb.net 代码中这样调用它
Public Function GetExistingdata(ByVal intuserId As Integer, ByVal startDate As String, ByVal enddate As String) As DataTable
Dim result As DataTable = Nothing
Try
result = New DataTable
'Initialize the connection and transation
If Not Me._IsInit Then
Me.Init()
Me._IsCommitHere = True
End If
Using command As New MySqlCommand("SP_EXTERNAL_WORK_DUTY_DETAILS_SELECT_EXISTING_DATA", Me._SQLConn, Me._SQLTran)
Dim Param As New MySqlParameter
command.CommandType = CommandType.StoredProcedure
Param = New MySqlParameter
Param.ParameterName = "@_user_id"
Param.MySqlDbType = MySqlDbType.Int32
Param.Direction = ParameterDirection.Input
Param.Value = clsCommon.ToInt(intuserId)
command.Parameters.Add(Param)
Param = New MySqlParameter
Param.ParameterName = "@_start_date"
Param.MySqlDbType = MySqlDbType.VarChar
Param.Direction = ParameterDirection.Input
Param.Value = clsCommon.ToStr(startDate)
command.Parameters.Add(Param)
Param = New MySqlParameter
Param.ParameterName = "@_end_date"
Param.MySqlDbType = MySqlDbType.VarChar
Param.Direction = ParameterDirection.Input
Param.Value = clsCommon.ToStr(enddate)
command.Parameters.Add(Param)
Dim SQLReader As MySqlDataReader = command.ExecuteReader
result.Load(SQLReader)
SQLReader.Close()
SQLReader = Nothing
End Using
Catch ex As MySqlException
'Dim str_funcs As String = Me.ToString
'clsErrorLog.ErrorLog(Me.fstrPageID, ex)
End Try
Return result
End Function
还有这个
Private Function CheckExistingData(ByVal intUserId As Integer, ByVal strtDate As String, ByVal endDate As String) As DataTable
Using checking As New clsExternalWorkDuty_func
Dim dt As New DataTable
dt = checking.GetExistingdata(intUserId, strtDate, endDate)
Return dt
End Using
End Function
然后我像这样在 ErrorFree() 函数中调用 CheckExistingData() 函数
Private Function ErrorFree() As Boolean
Dim check As New DataTable
check = CheckExistingData(lblhdddnuserid.Text, datepickerFrom.Text, datepickerto.Text)
If check.Rows.Count > 0 Then
DisplayMessage("Error", "Error", "Something went wrong, the data already exist. Please check and change the data.")
Return False
Exit Function
End If
Return True
End Function
最后，我在 btnSubmitExternalWorkDutyDetails_Click()
中调用了 ErrorFree() 函数