Understanding SQL JOINs is one of the most important skills when working with databases. This visual guide shows how different joins work between two tables A and B. 🔹 INNER JOIN Returns only the matching records from both tables. 🔹 FULL JOIN Returns all records from both tables, including matched and unmatched rows. 🔹 FULL JOIN (Unmatched Only) Returns records that exist in one table but not in the other. 🔹 LEFT JOIN Returns all records from the left table (A) and matched records from the right table (B). 🔹 LEFT JOIN (Only Unmatched) Returns records from table A that do not have matches in table B. 🔹 RIGHT JOIN Returns all records from the right table (B) and matched records from the left table (A). Visualizing joins like this makes them much easier to understand compared to reading only SQL queries. If you're learning SQL, Data Engineering, or Backend Development, mastering joins is essential. #SQL #Database #Programming #DataEngineering #BackendDevelopment #TechLearning #Developers
Good job. if we want to select the odd and even ids form tables how we can do this? and also. are we able to do this in sqlite
Good work
"Understanding SQL JOINs is one of ...." - understanding Joins is as fast as possible to forget Venn Diagrams for understanding Joins. Venn Diagrams were developed for explain the mathematical operations UNION, INTERSECT and DIFFERENCE (EXCEPT or MINUS in SQL). We have the following rules - the two operand tables have the same schema - t1(a,b,c) and t2(a,b,c) - the result tables has the same schema as well - result(a,b,c) - the result complies with the rules of a mathematical set - unique tuples/rows For join quit different rules - the two operand tables have different schema - t1(a,b,c) and t2(k,l,m,n,o) - the result tables has a schema with the UNION of the two operands attributes/column - result(a,b,c,k,l,m,n,o) - the result do not complies with the rules of a mathematical set - duplicates are allowed - but the most important is, that we for a join must specify a join condition As seen two very different rules and using the same diagram is just to make it more difficult to undestand. UNION t1 1,2 1,2 2,3 3,4 t2 2,3 5,1 t1 UNION t2 1,2 2,3 3,4 5,1 ------- t1 1,2,4 3,3,6 t2 1,4,A,G,23 2,6,B,F,117 INNER JOIN on first column 1,2,4,1,4,A,G,23 LEFT JOIN 1,2,4,1,4,A,G,23 3,3,6,NULL,NULL,NULL,NULL,NULL ...