c#数据库sqlserver连接公共类的实现

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Data.SqlClient; using System.Data; namespace _28CRM_System { class database { SqlConnection con; private void open()//开启 连接数据库 { if(con == null) { string constr = "server=localhost;database=CRM_database;user=sa;pwd=sa"; con = new SqlConnection(constr); } else if(con.State == System.Data.ConnectionState.Closed) { con.Open(); } } private void close()//数据库关闭 { if(con != null) { con.Close(); } } private SqlCommand createcommand(string sqlStr)//创建sql指令 { open(); SqlCommand com = new SqlCommand(sqlStr, con); return com; } public void runSql(string sqlStr)//执行sql语句 { SqlCommand cmd = createcommand(sqlStr); cmd.ExecuteNonQuery(); close(); } public int runSqlInt(string sqlStr)//返回行数 { SqlCommand cmd = createcommand(sqlStr); int t = (int)cmd.ExecuteScalar(); close(); return t; } public SqlDataReader runSql(string sqlStr,out SqlDataReader dr) { SqlCommand cmd = createcommand(sqlStr); dr = cmd.ExecuteReader(CommandBehavior.CloseConnection); return dr; } public DataTable ConvertDataReaderToDataTable(SqlDataReader datareader) { DataTable dt = new DataTable(); DataTable schemaTable = datareader.GetSchemaTable(); try { foreach(DataRow myRow in schemaTable.Rows) { DataColumn myDataColumn = new DataColumn(); myDataColumn.DataType = System.Type.GetType("System.String"); dt.Columns.Add(myDataColumn); } while (datareader.Read()) { DataRow mydataRow = dt.NewRow(); for(int i = 0; i < schemaTable.Rows.Count; i++) { mydataRow[i] = datareader[i].ToString(); } dt.Rows.Add(mydataRow); mydataRow = null; } schemaTable = null; datareader.Close(); return dt; } catch(Exception ex) { throw new Exception("转换出错", ex); } } } }