Set operators Union Minus Intersect match ALL COLUMNS must have same ID, column names

Which is better? Filter with many conditions Union, Intersect, Minus of multiple filters Efficiency?

SQL Review select [columns] from table1, [table2] where condition1 and condition2 group by columns

SQL Review (select [columns] from table1, [table2] where condition1 and condition2 group by columns ) union (... ) alternate syntax for join

Practice queries Each creature who can swim but not gargle Each creature who can swim and float Each creature who has achieved two skills Do these in SQL or GRAPE (if possible)

Times Cartesian product of two sets this is what SQL does when you don't specify a join condition Times + Filter = Match Join GRAPE problems

Practice queries Each creature who can swim but not gargle Each creature with the number of skills it has achieved Do these in SQL and then GRAPE (if possible)

Query planner Use indices to satisfy filter conditions Hash joins Optimize join order B trees

Data constistency Atomicity Entire transactions complete or fail Consistency Foreign key constrains satisfied Isolation Transactions isolated from each other Durability As soon as a transaction is done, it's done start transaction / end transaction

Experiment with Postgres!