Question

关于这个问题的一些建议：

select
    concat(MySourceTable,',',sid,'X',gid,'X',qid) as MySourceFieldname
from
    MySchemaTable
where
    SomeCriteria;

使用upper语句我得到一个字段名列表（仅一列）。如何将其转换为水平显示（彼此相邻的字段）位置，以逗号分隔我想生成一个'普通的“SELECT语句以供进一步使用。

@amixdon 输入是：

select concat('shape_survey_990113',sid,'X',gid,'X',qid) as lsfield -- <=MySourceFieldname
 from shape_questions -- <=MySchemaTable i.e. kind of dictionary
where question='result' -- <=SomeCriteria
  and sid=990113
  and language='en'
  order by lsfield;

输入结果如下（例如）

lsfields
---------
shape_survey_990113.990113X468X729,
shape_survey_990113.990113X469X733,
shape_survey_990113.990113X470X737,
....,

说明：sid，gid，qid是从与字典相当的表中获取的数字内容。这是我想要从中选择信息的源系统（不能更改）。它是一个开源调查工具。在此表中，处理每个调查的所有信息（数值990113正在识别许多中的一个特殊调查。上面的结尾是包含问题答案的最终字段名称。 'shape_survey_990113'是从以下位置选择firlds的表：

此选择结果应该看起来像是可以写入某个变量（例如SET @MyFields = ...）

shape_survey_990113.990113X235X476, shape_survey_990113.990113X235X484, shape_survey_990113.990113X235X496

..将在下一步中用于组成一个真正的选择语句，如：

concat('SELECT ', @MyFields, ' FROM shape_survey_991103;')

不幸的是我无法上传这个屏幕截图，没有足够的声誉......

Answer 1

对于

#include <opencv2\opencv.hpp>
#include <iostream>
#include<vector>

using namespace cv;  
using namespace std; 

int main(){

    VideoCapture capWebcam(0); 
    if (capWebcam.isOpened() == false){  
        cout << "Error: camera not detected!!\n" << endl;
        return -1;
    }

    Mat matOriginal;   // matrix object used to store image from webcam
    Mat matProcessed;
    vector<Vec3f> vecCircles;  

    namedWindow("Original"); //window for original image
    namedWindow("Processed"); //window for Processed image

    char charCheckForEscKey = 0;
    while (charCheckForEscKey != 27){   //as long as ESC is not pressed, stays in the while

        if (!capWebcam.read(matOriginal)){   
            cout << "Error: image frame not read!!" << endl;
            break;
        } //

        inRange(matOriginal,     //this time we don't need to pass a pointer; we pass the image as an object instead
            Scalar(0, 0, 175),    //specify the lower bound of BGR we want to keep
            Scalar(100, 100, 256), //upper bound of BGR
            matProcessed);    //return the processed image to another object

        GaussianBlur(matProcessed, matProcessed, Size(9, 9), 1.5, 1.5);  //take matProcessed image and blur by Gaussian filter(9x9 window with std of 1.5 in both x,y direction) and return to same object

        HoughCircles(matProcessed,
            vecCircles,   //use vector element to receive the x,y,radius of the detected circle
            CV_HOUGH_GRADIENT,  //algorithms used to detect circles
            2,                   //size of image divided by this value = "accumulator resolution"
            matProcessed.rows / 4,  //min distance between the centers of two detected circles
            100,       //upper pixel value threshold for canny edge detection to interpret as edge
            50,        //lower pixel value threshold for canny edge detection to interpret as edge
            10,        //min radius of a circle can be detected
            400);      //max radius of a circle can be detected

        for (const auto& circ : vecCircles)  //retrieve the x,y and radius of the detected circles from vecCircles object one by one
        {
            cout << "circle position x = " << circ[0]  //because itrCircles is a pointer(pass by reference), to get the value need to use * to dereference
                << ",y = " << circ[1]
                << ",r = " << circ[2] << "\n" << endl;

            // draw the center of detected circle in green
            circle(matOriginal, Point(circ[0], circ[1]), 3, Scalar(0, 255, 0), CV_FILLED);

            // draw the circumference of detected circle
            circle(matOriginal, Point(circ[0], circ[1]), circ[2], Scalar(0, 0, 255), 3);
        }

        imshow("Original", matOriginal);  //show the original mat(image)   in Original window
        imshow("Processed", matProcessed);// show the processed mat(image) in Processed window

        charCheckForEscKey = waitKey(10);  // delay 10 ms to allow a time gap to listen to any key pressed

    } // end while

    return(0);
} // end main

，没有什么神圣的，而且有点亵渎。失去它。并丢失引用的逗号。像这样。

CONCAT()

尽可能简单。

编写动态SELECT语句

1 个答案: