我们如何从getschemaTable获取Column Size和dataType？

我是一个新手，我试图从我的数据库中的某些表中检索列NAme，大小（最大legth）和DataType，当我执行它时，以下代码期望它显示所有列类型和名称（我没有找到如何引用Size，我使用了ColumnSize，但据说DataColumn不包含此方法的定义）但在执行时，它只显示：IsColumnSetSystem.Boolean这是代码：

private void button1_Click(object sender, EventArgs e) { string EF = textBox1.Text; try{ //SqlDataAdapter adapter = SetupDataAdapter("SELECT * FROM id_declarant"); SqlCommand comm = new SqlCommand(); string connectionString = @"Data Source=.\SQLEXPRESS;Initial Catalog=declaration;Integrated Security=True"; comm.Connection=new SqlConnection(connectionString); String sql = @"SELECT * FROM id_declarant,declarant WHERE (declarant.Nom_pren_RS='" + EF + "') and (id_declarant.mat_fisc=declarant.mat_fisc) "; comm.CommandText = sql; comm.Connection.Open(); SqlDataReader reader = comm.ExecuteReader(); DataTable schemaTable = reader.GetSchemaTable(); foreach (DataRow row in schemaTable.Rows) { foreach (DataColumn column in schemaTable.Columns) { System.IO.File.WriteAllText(@"C:\Users\Manuela\Documents\GL4\WriteLines.txt", column.ColumnName + column.DataType ); } } 

Answer 1

您正在打印由GetSchemaTable返回的数据表的列名，而不是其值，我建议使用StringBuilder并在退出循环时写入所有内容

  StringBuilder sb = new StringBuilder(); foreach (DataRow row in schemaTable.Rows) { foreach (DataColumn column in schemaTable.Columns) { sb.AppendLine(column.ColumnName + ":" +row[column.ColumnName].ToString()); } sb.AppendLine(); } File.WriteAllText(@"C:\Users\Manuela\Documents\GL4\WriteLines.txt", sb.ToString()); 

Answer 2

也许我对这个有点偏僻但要获得列的名称，大小和数据类型，你可以试试这个：

 DataTable schemaTable = reader.GetSchemaTable(); foreach (DataRow row in schemaTable.Rows) { var name = row["ColumnName"]; var size = row["ColumnSize"]; var dataType = row["DataTypeName"]; //append these to a string or StringBuilder for writing out later... } 

但也许这不是你想要的？