SQL HELP

Suppose the following tables are part of a project management database of a company, where keys are underlined: E(ssn, name, salary) stores the information of employees, P(pid, title, budget) stores the information of projects, and M(ssn, pid, start, end) stores the information of management of projects by employees. 1) Write a relational algebra expression to return the pids of projects that are managed by employee "Jack" but not by "Mary". 2) Write a relational algebra expression to return the names of those employees who does 3) 4) Write a relational algebra expression to return the pids of those projects that are managed 5) Write an SQL query to return the ssns of employees that manage at least two projects, 6) Write an SQL query to return the ssns of employees that managed at most 1 project 7) Write an SQL query to return the ssns of employees that managed no project in last 6 8) Write an SQL query to return the name of employees that managed only 1 project which 9) Write a SOI query to give everyone a 10% salary who managed 2 projects to completion 10) Write an SQL query to delete all the projects from table P that are NOT managed by any 11) Define an SQL view PNum (pid,num) that gives the number of employees that manages 12) Write an SQL query to return the ssn of employees that manage each project in P. not manage any project. Write a relational algebra expression to return the names of those employees who manage at least two projects. by an employee with a salary great than S100,000. one is finished (end