檢查MS Access數據庫表是否存在創建它

Question

如何以編程方式檢查MS Access數據庫表是否存在，然後創建它？

Answer 1

簡單的執行下面的代碼，如果表將存在，它將返回其他方法錯誤，將創建一個新的：如果一個表已經存在

try 
{ 
     OleDbConnection myConnection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + frmMain.strFilePath + "\\ConfigStructure.mdb"); 
     myConnection.Open(); 
     OleDbCommand myCommand = new OleDbCommand(); 
     myCommand.Connection = myConnection; 
     myCommand.CommandText = "CREATE TABLE <yourtable name>(<columns>)"; 
     myCommand.ExecuteNonQuery(); 
     myCommand.Connection.Close(); 
} 
catch(OleDbException e) 
{ 
    if(e.ErrorCode == 3010 || e.ErrorCode == 3012) 
    // if error then table exist do processing as required 
} 

這些錯誤代碼返回 - check here所有。

Answer 2

您可以遍歷表名來檢查特定的表。請參閱下面的代碼來獲取表名。

 string connectionstring = "Your connection string"; 
     string[] restrictionValues = new string[4]{null,null,null,"TABLE"}; 
     OleDbConnection oleDbCon = new OleDbConnection(connectionString); 
     List<string> tableNames = new List<string>(); 

     try 
     { 
      oleDbCon.Open(); 
      DataTable schemaInformation = oleDbCon.GetSchema("Tables", restrictionValues); 

      foreach (DataRow row in schemaInformation.Rows) 
      { 
       tableNames.Add(row.ItemArray[2].ToString()); 
      } 
     } 
     finally 
     { 
      oleDbCon.Close(); 
     }   

Answer 3

爲了完整起見，我會指出，前陣子我貼4種不同的編碼了TableExists() function within Access的方式。在MSysObjects上運行SQL SELECT的版本可以從外部訪問，儘管在某些情況下，您可能會遇到安全錯誤（因爲您不允許訪問Jet/ACE系統表）。

Answer 4

要檢查表存在，你可以這樣延伸的DbConnection：

public static class DbConnectionExtensions 
{ 
    public static bool TableExists(this DbConnection conn, string table) 
    { 
     conn.open(); 
     var exists = conn.GetSchema("Tables", new string[4] { null, null, table, "TABLE" }).Rows.Count > 0; 
     conn.close(); 
     return exists; 
    } 
} 

然後就可以調用TableExists在這樣的OleDbConnection，SQLiteConnection或SqlConnection的任何派生類。

Answer 5

一個簡單的方法做，這是

public bool CheckTableExistance(string TableName) 
    { 
     // Variable to return that defines if the table exists or not. 
     bool TableExists = false; 

     // Try the database logic 
     try 
     { 
      // Make the Database Connection 
      ConnectAt(); 

      // Get the datatable information 
      DataTable dt = _cnn.GetSchema("Tables"); 

      // Loop throw the rows in the datatable 
      foreach (DataRow row in dt.Rows) 
      { 
       // If we have a table name match, make our return true 
       // and break the looop 
       if (row.ItemArray[2].ToString() == TableName) 
       { 
        TableExists = true; 
        break; 
       } 
      } 

      //close database connections! 
      Disconnect(); 
      return TableExists; 
     } 
     catch (Exception e) 
     { 
      // Handle your ERRORS! 
      return false; 
     } 
    }