System.Data.SqlClient.SqlException:““（”附近有语法错误。” ！

Question

    private string sql;
    private void toolStripButton1_Click(object sender, EventArgs e)
    {
        sql = "SELECT tb_ShangPingInfo. 商品名称, tb_ShangPingInfo. 单价, Sum(tb_XiaoShouInfo. 销售数量) As[销售数量合计], " +
            "tb_XiaoShouInfo. 销售员, （Sum (tb_XiaoShouInfo. 销售数量) * tb_ShangPingInfo. 单价) As[销售金额]" +
            "FROM tb_ShangPingInfo JOIN tb_XiaoShouInfo ON tb_ShangPingInfo. [id]=tb_XiaoShouInfo. [商品id]" +
            " AND (tb_ShangPingInfo.商品名称 LIKE '%" + toolStripTextBox1.Text + "%') " +
            " AND (tb_ShangPingInfo.销售员 LIKE '%" + toolStripTextBox2.Text + "%') " +
            " WHERE(tb_ShangPingInfo.销售日期 BETWEEN '" + dateTimePicker1.Value + "' AND '" + dateTimePicker2.Value + "') " +
            " GROUP BY tb_ShangPingInfo.商品名称, tb_ShangPingInfo.单价, tb_XiaoShouInfo.销售员;";
        ShowInfo(sql);
    }
    private void ShowInfo(string sql)
    {
        SqlConnection con = new SqlConnection("Data Source=DESKTOP-R781PCS;DataBase=db_EMS;User ID=sa;PWD=123");
        SqlDataAdapter dap = new SqlDataAdapter(sql, con);
        DataSet ds = new DataSet();
        dap.Fill(ds);
        dataGridView1.DataSource = ds.Tables[0].DefaultView;
    }

Answer 1

明显是中文下的括号。切换到英文状态下，再添加括号。跟其他括号对比一下，是不是不一样。