   SQL. 18   
 


        SQL.  18    :  ,  SKU, , , , , , ,       .     SQLite.





 

   SQL. 18   





  





    


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SQL    , ,  ,       ,      .

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      SQLite   .




  


1.     (#task-1)

2.   SKU (#task-2)

3.     (#task-3)

4.     (#litres_trial_promo)

5.    (#litres_trial_promo)

6.       (#litres_trial_promo)

7.     (#litres_trial_promo)

8.    (#litres_trial_promo)

9.      SKU (#litres_trial_promo)

10.    (#litres_trial_promo)

11.     (#litres_trial_promo)

12.      (#litres_trial_promo)

13.    (#litres_trial_promo)

14.     (#litres_trial_promo)

15.      (#litres_trial_promo)

16.    (#litres_trial_promo)

17.     (#litres_trial_promo)

18.     (#litres_trial_promo)




 





 1.    



 

  ,        .




CREATE TABLE products(sku TEXT, title TEXT);

INSERT INTO products VALUES ('A1',''),('B2',''),('C3','   ');




SELECT sku

FROM products

WHERE trim(title) = ''

ORDER BY sku;


 

[["B2"], ["C3"]]


 

trim    ,       .

     ,         SQLite.

 ORDER BY      ,        .


  

 title IS NULL  ,     NULL,     .


 

 SKU ?        .

: B2  C3.        .




 2.   SKU



 

  ,         .




CREATE TABLE products(sku TEXT, title TEXT);

INSERT INTO products VALUES ('A1',''),('A1',' v2'),('B2','');




SELECT sku, COUNT(*) AS rows_count

FROM products

GROUP BY sku

HAVING COUNT(*) > 1

ORDER BY sku;


 

[["A1", 2]]


 

GROUP BY sku    ,  HAVING  .

     ,         SQLite.

 ORDER BY      ,        .


  

DISTINCT sku   ,         .


 

 SKU ?        .

: A1.        .




 3.    



 

  ,         .




CREATE TABLE products(sku TEXT, category TEXT);

INSERT INTO products VALUES ('A1',''),('B2',NULL),('C3','');




SELECT sku

FROM products

WHERE category IS NULL OR trim(category) = ''

ORDER BY sku;


 

[["B2"], ["C3"]]


 

   NULL,     trim.

     ,         SQLite.

 ORDER BY      ,        .


  

NULL      ,   SQL   .


 

 SKU  ?        .




  .


   .

   ,     (https://www.litres.ru/book/raznoe/kachestvo-kataloga-v-sql-18-zadach-dlia-kartochek-74419933/)  .

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