SQL Server使用情况，如果ASP.NET中不存在？

Question

Is there is something wrong in my sql Query ? I am having an error:

Incorrect syntax near the keyword 'join'.

  protected void Button1_Click1(object sender, EventArgs e)
    {
        foreach (GridViewRow row in GridView1.Rows)
        {
            if ((row.FindControl("CheckBox1") as CheckBox).Checked)
            {
                //string prNB = Session["prnb"].ToString();
                SqlCommand cmd = new SqlCommand("insert into PrescTest(Test, idPresc)select @Test, idPresc from Prescription where prNB = @prNB and not exists(select test from PrescTest pt,join Prescription p on pt.idPresc = p.idPresc where prNB = @prNB)", conn);
                cmd.Parameters.Add("Test", SqlDbType.NVarChar, 50).Value = row.Cells[2].Text;
                cmd.Parameters.Add("prNB", SqlDbType.NVarChar, 50).Value = Session["prnb"].ToString();
                conn.Open();
                cmd.ExecuteNonQuery();
                conn.Close();
            }
        }
        Response.Redirect("PrescForm.aspx");
    }

Sql tables diagram:

Answer 1

There are several things wrong in your sql statement.

• the usage of string concatenation instead of a parameter.
• the usage of implicit (old style) join. Explicit joins are a part of Ansi-Sql for well over 25 years now (approaching 30, I believe) so there really is no excuse to write implicit joins.
• the usage of a subquery inside the values clause - instead of simply insert...select .
• the fact that you run this query for every row in your grid, instead of collecting the data from the grid into a collection and run a single insert...select statement
• the begin and end keywords define a code block, much like { and } in c# - the open parenthesis right after the begin keyword is a redundant (and I think also a syntax error). same goes for the close parenthesis after the end keyword

A quick fix of your SQL statement is this:

insert into PrescTest (Test,idPresc) 
select @Test, idPresc 
from Prescription 
where prNB = @prNB
and not exists(
    select test 
    from PrescTest pt 
    join Prescription p 
        on pt.idPresc = p.idPresc
    where prNB = @prNB 
)

Note that the not exists have moved into the where clause so there really is no need for the if .

Please note that this doesn't address the fact that you are running this sql for each row individually - you should look up table valued parameters to fix that issue.

Answer 2

Here is your query. It will work

if not exists(select test from PrescTest pt, Prescription p where prNB ="+ prNB +"and pt.idPresc = p.idPresc) begin insert into PrescTest (Test,idPresc) values (@Test,(select idPresc from Prescription where prNB=" + prNB + "))end

Answer 3

在“结束”之前缺少两个右括号？

... + prNB + "))end))", conn);