C# 如果在 SQL 更新中可用，否则插入

Question

我已经检查了 Stackoverflow 上的许多帖子，但我仍然坚持下面的查询。我是学习 C# 的初学者，希望得到帮助。

Error: Incorrect Syntax near keyword ELSE

我正在尝试检查是否应该执行下面的问题 1 或问题 2(如果选择了其中一个)。还有一次它给了我一个错误 @answer2 not defined。

string query = @"IF EXISTS(SELECT * FROM dbo.tbl_pkt_Answers_Submitted  WHERE (Questions = @Question1 or Questions = @Question2))

    UPDATE dbo.tbl_pkt_Answers_Submitted 
    SET AnswersSubmitted = @Answer1
    WHERE Questions = @Question1;

    UPDATE dbo.tbl_pkt_Answers_Submitted 
    SET AnswersSubmitted = @Answer2
    WHERE Questions = @Question2;

    ELSE

    INSERT INTO dbo.tbl_pkt_Answers_Submitted(Questions, AnswersSubmitted)   
    VALUES (@Question1, @Answer1), (@Question2, @Answer2);";

SqlCommand cmd = new SqlCommand(query, con);

cmd.Parameters.Add("@Question1", lblQuestion1.Text);
cmd.Parameters.Add("@Question2", lblQuestion2.Text);

if (rdq1a1.Checked)
{
    cmd.Parameters.Add("@Answer1", rdq1a1.Text);
}

if (rdq1a2.Checked)
{
    cmd.Parameters.Add("@Answer1", rdq1a2.Text);
}

if (rdq1a3.Checked)
{
    cmd.Parameters.Add("@Answer1", rdq1a3.Text);
}

if (rdq1a4.Checked)
{
    cmd.Parameters.Add("@Answer1", rdq1a4.Text);
}

if (rdq2a1.Checked)
{
    cmd.Parameters.Add("@Answer2", rdq2a1.Text);
}

if (rdq2a2.Checked)
{
    cmd.Parameters.Add("@Answer2", rdq2a2.Text);
}

if (rdq2a3.Checked)
{
    cmd.Parameters.Add("@Answer2", rdq2a3.Text);
}

if (rdq2a4.Checked)
{
    cmd.Parameters.Add("@Answer2", rdq2a4.Text);
}

con.Open();
cmd.ExecuteNonQuery();

MessageBox.Show("Your Data has been saved");
con.Close();

Answer 1

IF 语句的 'true' 部分包含多个 SQL 语句，您必须将这些语句括在 BEGIN 和 END 中

string query = @"IF EXISTS(SELECT * FROM dbo.tbl_pkt_Answers_Submitted  WHERE (Questions = @Question1 or Questions = @Question2))
                 BEGIN
                    UPDATE dbo.tbl_pkt_Answers_Submitted 
                    SET AnswersSubmitted = @Answer1
                    WHERE Questions = @Question1;

                    UPDATE dbo.tbl_pkt_Answers_Submitted 
                    SET AnswersSubmitted = @Answer2
                    WHERE Questions = @Question2;
                 END
                 ELSE
                    INSERT INTO dbo.tbl_pkt_Answers_Submitted(Questions, AnswersSubmitted) 
                    VALUES(@Question1, @Answer1), (@Question2, @Answer2);";