In a sql database give an example of a search problem that will work with an inner join and will not work with an outer join. How would you write the query? Why does the search fail or succeed?

True or False below: Given two relations named A and B, if we q-JOIN A and B, the maximum number of attributes in the result relation could be (the number of attributes of A) times(*) the number of attributes of B).  * in an SQL SELECT statement means “all the tuples”.   In relational algebra, Cartesian Product (X) can be implemented using the q-JOIN operator.  Cartesian Product ISA q-JOIN where q-condition always evaluates to true. SQL is based on Predicate Calculus. A query in SQL always specifies what should be included in the query result.

My other instruction for SQL says: Create and test a stored procedure called checkin_transaction that processes a “checkin” transaction. When a book is checked in, the corresponding CHECKOUT record is updated to show the date it was checked in, and the Pat_ID attribute in the BOOK table is updated to NULL.  The entire transaction (starting with START TRANSACTION; and ending with COMMIT;) should be in between the BEGIN and END statements of the stored procedure.  You should be able to call the procedure with a statement like this, passing the values of the Book_Num, Pat_ID, and Check_In_Date to the procedure:   CALL checkin_transaction(5243, 1170, ‘2017-04-30’) Do you guys know how?

Using php and sql:  Create a PDO object to connect to your database for running select queries.Write a database query to output all the messages in the messages table.