Question

如何执行以下SQL查询？

Update my_table 
set columnA = 1 
where columnID in (select columnID, count(columnID) 
                   from my_table  
                   group by columnID 
                   having count(columnID) = 1)

感谢您的帮助

Answer 1

您必须匹配比较两侧的字段数。在这种情况下，您可以删除count(*)，因为您无需在having子句中选择它以使用它。

Update my_table 
set columnA = 1 
where columnID in (select columnID 
                   from my_table 
                   group by columnID     
                   having count(columnID) = 1)

Answer 2

请尝试此查询

import pytesseract
import cv2

originalImg = cv2.imread('tp.png')
originalImg = cv2.resize(originalImg, None, fx=2.5, fy=2.5)
img = cv2.cvtColor(originalImg, cv2.COLOR_BGR2GRAY)
_,img = cv2.threshold(img,100,255,cv2.THRESH_BINARY)

h, w = img.shape

letters = pytesseract.image_to_boxes(img)
letters = letters.split('\n')
letters = [letter.split() for letter in letters]

for letter in letters:    
    cv2.rectangle(originalImg, (int(letter[1]), h - int(letter[2])), (int(letter[3]), h - int(letter[4])), (0,0,255), 1)

cv2.imshow('', originalImg)

使用Select更新SQL查询

2 个答案: