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[英]Error when get connection string: ArgumentNullException: Value cannot be null. Parameter name: connectionString
[英]ConnectionString = Null when i used Connection method more than 1 time
我的連接字符串有問題,我有一個帶有字符串參數的Execute方法來接收查詢,
public class Create_Connection
{
public static readonly string CONN_STRING =
ConfigurationManager.ConnectionStrings["TaskConnectionString"].ConnectionString;
public static readonly SqlConnection SqlConn = new SqlConnection(CONN_STRING);
public static readonly SqlConnection CONN = new SqlConnection(CONN_STRING);
public DataSet ExecuteSql(string sql)
{
SqlDataAdapter da;
DataSet ds;
if (CONN.State == ConnectionState.Open)
CONN.Close();
CONN.Open();
da = new SqlDataAdapter(sql, CONN_STRING);
ds = new DataSet();
da.Fill(ds);
CONN.Dispose();
CONN.Close();
return ds;
}
}
當我第一次使用它的時候,它將起作用,但是當第二次查詢的時候使用Execute方法時,我的程序停止運行並給我這個Masseg:“ ConnectionString屬性尚未初始化”! 和InnerException:“ null”!
第一次使用時如何實現,然后在連接字符串為“靜態只讀”時更改呢!
並提前感謝:) ..
不要使用靜態SqlCOnnection。
public class Create_Connection
{
public static readonly string CONN_STRING = ConfigurationManager.ConnectionStrings["TaskConnectionString"].ConnectionString;
public static readonly SqlConnection SqlConn = new SqlConnection(CONN_STRING);
//public static readonly SqlConnection CONN = new SqlConnection(CONN_STRING);
public DataSet ExecuteSql(string sql)
{
SqlDataAdapter da;
DataSet ds;
using (var CONN = new SqlConnection(CONN_STRING)) {
//if (CONN.State == ConnectionState.Open)
// CONN.Close();
CONN.Open();
da = new SqlDataAdapter(sql, CONN_STRING);
ds = new DataSet();
da.Fill(ds);
//CONN.Dispose();
CONN.Close();
}
return ds;
}
}
並在使用時創建變量。 像這樣
public class Create_Connection
{
public static readonly string CONN_STRING = ConfigurationManager.ConnectionStrings["TaskConnectionString"].ConnectionString;
public static readonly SqlConnection SqlConn = new SqlConnection(CONN_STRING);
public DataSet ExecuteSql(string sql)
{
var ds = new DataSet();
using (var CONN = new SqlConnection(CONN_STRING)) {
CONN.Open();
var da = new SqlDataAdapter(sql, CONN_STRING);
da.Fill(ds);
CONN.Close();
}
return ds;
}
}
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