使用C＃更新SQL表中的值使用C＃

Question

我需要將我的字段QB_STATUS從值R更改爲值C。我這樣做是因爲我無法「重新查詢」表格，因爲數據可能已經改變。

我建立了一個更新條目列表。該代碼不會出錯，並重復5次（基於我的idInvoices列表正確），但該字段不會更新。

for (int i = 0; i < idInvoices.Count; i++) 
{ 
    // following command will update one row as ID_Invoice is primary key. 
    // ID_Invoice taken from list previously built in ReadDataToNAVArray 
    SqlCommand cmd = new SqlCommand("UPDATE tblINVOICES SET QB_STATUS=@Status WHERE ID_INVOICE = @IDInvoice", myConnection); 
    cmd.Parameters.Add("@Status", "C"); 
    cmd.Parameters.Add("@IDInvoice", idInvoices[i]); 

    cmd.Dispose(); 
} 

Answer 1

你缺少的ExecuteNonQuery在你的命令。

for (int i = 0; i < idInvoices.Count; i++) 
{ 
    SqlCommand cmd = new SqlCommand("UPDATE tblINVOICES SET QB_STATUS=@Status WHERE ID_INVOICE = @IDInvoice", myConnection); 
    cmd.Parameters.Add("@Status", "C"); 
    cmd.Parameters.Add("@IDInvoice", idInvoices[i]); 
    cmd.ExecuteNonQuery(); 
    cmd.Dispose(); 
} 

Answer 2

首先，你必須執行查詢：ExecuteNonQuery;第二 - 不創建命令，參數等內環路，只是分配值並執行：

// Make SQL readable 
String sql = 
    @"UPDATE tblINVOICES 
     SET QB_STATUS = @Status 
     WHERE ID_INVOICE = @IDInvoice"; 

// wrap IDisposable into "using" 
// do not recreate command in the loop - create it once 
using (SqlCommand cmd = new SqlCommand(sql, myConnection)) { 
    cmd.Parameters.Add("@Status", SqlDbType.VarChar); //TODO: check types, please 
    cmd.Parameters.Add("@IDInvoice", SqlDbType.Decimal); //TODO: check types, please 

    // Assign parameters with their values and execute 
    for (int i = 0; i < idInvoices.Count; i++) { 
    cmd.Parameters["@Status"].Value = "C"; 
    cmd.Parameters["@IDInvoice"].Value = idInvoices[i]; 

    cmd.ExecuteNonQuery(); 
    }  
} 

Answer 3

我想你錯過cmd.ExecuteNonQuery();。

使用SQL命令的不同方式的例子：

SqlConnection addConn = new SqlConnection(); 
      addConn.ConnectionString = Properties.Settings.Default.yourDataBaseConnection; 
      addConn.Open(); 

      SqlCommand addComm = new SqlCommand(); 
      addComm.Connection = addConn; 
      addComm.CommandText = "sql command"; 
      addComm.ExecuteNonQuery();