Map it to a query tree Provide a simplified WHERE clause

Grace hash join is usually the best algorithm for joins in which the join condition includes an inequality (i.e. col1 < col2). Group of answer choices True False

Modify the recursive query in Figure 5.16 to define a relationprereq_depth(course_id, prereq_id, depth) where the attribute depth indicates how many levels of intermediate prerequisites there are between the course and the prerequisite. Direct prerequisites havea depth of 0. Note that a prerequisite course may have multiple depths and thusmay appear more than once.

SQL: Create a SQL query that uses an uncorrelated subquery and no joins to display the descriptions for products provided by a vendor in area code 615. Remember, the main difference between a correlated subquery and uncorrelated subquery is that, in a correlated subquery, the inner query is dependent upon the outer query, while, with an uncorrelated query, the inner query does not depend upon the outer query. Instead, it runs just once. You should NOT use union, minus, or intersect in this query. The outer query will use the PRODUCT table and the inner query will use the VENDOR table [hint: you should have 9 records of output].   My code: select p_descript from product where (select v_areacode from vendor where v_areacode = '615' ; I am getting this error, problem is I can't see what is missing any assistance is appreciated.  ORA-00936: missing expression

A.   The relation R(a,b) may have duplicate tuples. Which of the following queries has a result that is guaranteed not to have duplicates, regardless of what tuples R contains?       a) SELECT a, AVG(b) FROM R GROUP BY a     b) SELECT b FROM R WHERE a = b     c) SELECT a FROM R WHERE a >= ALL (SELECT a FROM R)     d) SELECT a FROM R WHERE a = 1   B.   Relation R(a,b) has no duplicate tuples, although neither a nor b is a key. Relation S(c,d) may have duplicates. Which of the following queries is guaranteed to produce no duplicates?       a) SELECT c, d FROM S WHERE c IN (SELECT a FROM R) AND d IN (SELECT b FROM R)     b) SELECT S.c, S.d FROM R, S WHERE R.a = S.d AND R.b = S.c     c) SELECT c FROM S WHERE c = d     d) SELECT c, d FROM S GROUP BY c, d

Emp-ID Course-Title Name Dept-Name Salary Date-Completed • Convert the relation to the second normal form.

Course • Courseld CourseCode CourseName Capacity Instructorld 3815 ENGL862 American Literature 75 2 2213 CS8 Computer Graphics 25 1 4093 PHIL26 Intro to Philosophy 150 3 8131 CS58 Databases 50 7152 PHIL276 Ethics 100 3 • Instructorld 123 Instructor InstructorName Rank Ben Love Associate Professor Pat Wade Mai Wood Associate Professor Professor Department Computer Science English Philosophy Note: Both tables may not be necessary to complete this level. Complete the following correlated subquery to find instructors who teach fewer than 2 courses. The query should return the row containing Pat Wade. SELECT * FROM Instructor I WHERE 2 > (SELECT *Type your code here */ FROM Course WHERE InstructorId =