SqlConnection con = DB.WebConnection();//通过类调用连接上数据库 con.Open();//打开连接 SqlCommand com = new SqlCommand(); string sqlgetround = "select max(round) as max from Product where season= 'summer'"; com.CommandText = sqlgetround; com.CommandType = CommandType.Text; com.Connection = con; SqlDataReader reader = com.ExecuteReader(); if (reader.Read()) { string max = reader["max"].ToString(); } 随便写的 基础的东西先好好学下吧,一下写不出来也要能马上在网上查到
SqlConnection con = DB.WebConnection();//通过类调用连接上数据库
con.Open();//打开连接
SqlCommand com = new SqlCommand();
string sqlgetround = "select max(round) as max from Product where season= 'summer'";
com.CommandText = sqlgetround;
com.CommandType = CommandType.Text;
com.Connection = con;
SqlDataReader reader = com.ExecuteReader();
if (reader.Read())
{
string max = reader["max"].ToString();
}
随便写的
基础的东西先好好学下吧,一下写不出来也要能马上在网上查到
一定要记得,使用"as"给新字段重命名,因为使用max后的字段是没有名称,要重命名后才可以调用
string sqlcheck = "select * from Product where season= 'summer'";
SqlCommand cmdcheck = new SqlCommand(sqlcheck, conn);
SqlDataReader rdr1 = cmdcheck.ExecuteReader();
SqlDataReader rdr1 = cmdcheck.ExecuteReader();
bool result = rdr1.HasRows;
rdr1.Close();result为ture则有记录。
总是出错。用int max =convert.toint32()+1也不行。
string roundno; if (result)
{
string sqlgetround = "select max(roundno)+1 as max from Product where season= 'summer'";
SqlCommand cmdround = new SqlCommand(sqlgetround, conn);
SqlDataReader rdr2 = cmdround.ExecuteReader();
roundno = rdr2["max"].ToString();
// roundno = "1";
rdr2.Close();
Response.Write("found");
}
else
{
roundno = "1";
Response.Write("no found");
}
可能没有值,也可能是刚才别名max是关键字的原因
SqlDataReader rdr2 = cmdround.ExecuteReader();
后面的
if (rdr2.Read())