If columns having same names have different data types, it returns error

Natural joins are not based on primary/foreign keys

It selects rows from the two tables having different values in the matched columns

Natural join is based on all columns in two tables having same name

It is recommended that aliases be keywords to keep the statement uniform throughout the query

Put join conditions before other conditions in the WHERE clause when using implicit join

It is recommended that joins between tables are based on Primary/Foreign keys

Any table listed in a join condition MUST exist in the FROM clause when using implicit join

Combines the output from multiple queries and must include the same number of columns

Combines the output from multiple queries and does not include the same number of columns

Combines the output from no more than two queries and does not include the same number of columns

Combines the output from no more than two queries and must include the same number of columns

CROSS JOIN

OUTER JOIN

INNER JOIN

SELF JOIN

Group functions ignore null values

DISTINCT keyword makes a group function consider duplicate values

Group functions operate on sets of rows to produce multiple results per group

select * from customers left join orders on orders.customer_id = customers.customer_id where orders.order_id is not null;

select * from customers left join orders on orders.customer_id = customers.customer_id;

select * from customers join orders on orders.customer_id = customers.customer_id;

select * from customers left join orders on orders.customer_id = customers.customer_id where orders.order_id is null;

select count(distinct customers.customers_id) from customers join orders on orders.customer_id = customers.customers_id;

select count(*) from customers join orders on orders.customer_id = customers.customer_id;

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