沒有獲得特定表的列

Question

我想獲取特定表的模式，但我列爲空。

Reference

我試圖讓導致這下面類：

public class Tables 
    { 
     public string Name { get; set; } 
     public string[] Columns { get; set; } 
    } 

代碼：

string[] selectedTables = { "Table1", "Table2"}; 
    var conectionString = new SqlConnection("MyconnectionString"); 
    var data = new List<Tables>(); 
    data = conectionString.GetSchema("Tables").AsEnumerable() 
     .Select 
     (
     t => new Tables 
     { 
      Name = t[2].ToString(), 
      Columns = conn.GetSchema("Columns", 
        new string[] { databaseName,t[2].ToString() }).AsEnumerable() // t[2].ToString() represent tablename 
        .Where(c => selectedTables.Contains(t[2].ToString())) 
        .Select(c => c[3].ToString()).ToArray() // c[3].ToString() represent Columns 
     }).ToList(); 

return data; 

雖然在數據我收到表的列表，即Table0,Table1,Table2,Table3等。但我沒有得到這個Table1 and Table2選定的表的列。

更新：我正在尋找這樣的事情：

// You can specify the Catalog, Schema, Table Name, Table Type to get 
     // the specified table(s). 
     // You can use four restrictions for Table, so you should create a 4 members array. 
     String[] tableRestrictions = new String[4]; 

     // For the array, 0-member represents Catalog; 1-member represents Schema; 
     // 2-member represents Table Name; 3-member represents Table Type. 
     // Now we specify the Table Name of the table what we want to get schema information. 
     tableRestrictions[2] = "Course"; 

     DataTable courseTableSchemaTable = conn.GetSchema("Tables", tableRestrictions); 

data = conectionString.GetSchema("Tables").AsEnumerable() 
     .Select 
     (
     t => new Tables 
     { 
      Name = t[2].ToString(), 
      Columns = (from useTable in selectedTables 
      let columns = conn.GetSchema("Columns",new string[] { databaseName, t["TABLE_SCHEMA"].ToString(), useTable }) 
        select new { columns[3]}) //Error 
     }).ToList(); 

如何注入我selectedTables？

Answer 1

有幾種方法可以完成這個目標。

的一種方法是讓所有的表，該表的名稱過濾結果，然後得到每個選定表中的列：

string[] selectedTables = { "Table1", "Table2"}; 
using (var conection = new SqlConnection("MyconnectionString")) 
{ 
    connection.Open(); 

    var tables = (
     from table in connection.GetSchema("Tables").AsEnumerable() 
     let name = (string)table["TABLE_NAME"] 
     where selectedTables.Contains(name) 
     let catalog = (string)table["TABLE_CATALOG"] 
     let schema = (string)table["TABLE_SCHEMA"] 
     select new Tables // this should really be called Table 
     { 
      Name = name, 
      Columns = (
       from column in connection.GetSchema("Columns", new [] { catalog, schema, name }).AsEnumerable() 
       select (string)column["COLUMN_NAME"]).ToArray() 
     }).ToList(); 

    return tables; 
} 

更新：按照評論，你真正想要的所有表，但僅填充了選定的列，所以不是where您可以使用相同的標準條件列人口：

 from table in connection.GetSchema("Tables").AsEnumerable() 
     let name = (string)table["TABLE_NAME"] 
     let catalog = (string)table["TABLE_CATALOG"] 
     let schema = (string)table["TABLE_SCHEMA"] 
     select new Tables // this should really be called Table 
     { 
      Name = name, 
      Columns = selectedTables.Contains(name) ? (
       from column in connection.GetSchema("Columns", new [] { catalog, schema, name }).AsEnumerable() 
       select (string)column["COLUMN_NAME"]).ToArray() : null 
     }).ToList();