c#查询sql server数据库中的数据时，字段名能否使用变量？?

private void insertfuzhu(string item,string tb)
        {
database db = new database();
string insertsql = "insert into fuzhu(patient_id,times,'" + item + "')values('" + patid.Text + "','" + times.Text + "','" + tb + "')')";
            string updasql = "update fuzhu set '" + item + "'='" + tb + "' where patient_id='" + patid.Text + "'and times='" + times.Text + "'')";
            string sql = "select count(*) from fuzhu where patient_id='" + patid.Text + "'and times='" + times.Text + "'";
            int a = 0;
            a = db.runsqlint(sql);
            if (a > 0)
            {
                db.runsql(updasql);
            }
            else
            {
                db.runsql(insertsql);
            }
        }
//其中item为表中的字段名，使用变量作为字段名后无法执行查询，新手，不知道怎么办，请大神指教

private void insertfuzhu(string item,string tb)


        {

database db = new database();


string insertsql = "insert into fuzhu(patient_id,times," + item + ")values('" + patid.Text + "','" + times.Text + "','" + tb + "')')";


            string updasql = "update fuzhu set " + item + "='" + tb + "' where patient_id='" + patid.Text + "'and times='" + times.Text + "'')";


            string sql = "select count(*) from fuzhu where patient_id='" + patid.Text + "'and times='" + times.Text + "'";


            int a = 0;


            a = db.runsqlint(sql);


            if (a > 0)


            {

                db.runsql(updasql);


            }


            else


            {

                db.runsql(insertsql);


            }


        }


//其中item为表中的字段名，使用变量作为字段名后无法执行查询，新手，不知道怎么办，请大神指教

可以

但你定义的变量名称=字段名称

这个字段名称数据库内一定要存在。否则会出错。

字段名不需要+'