Write a SQL query that would display only each unique salary from an employee table.

SQL ( ORACLE SQL DEVELOPER ) :  THIS IS FIRST , SECOND AND THIRD TABLE for the Task 1 to solve  :    create table author_45( auth_name char(50), gender char(1), age number(3), nationality char(50), PRIMARY KEY (auth_name) );     create table book_45( isbn number(10), title char(50), ver_no number(2), publisher char(50), PRIMARY KEY (isbn) );     create table writtenBy_45( isbn number(10), auth_name char(50), yr_published number(4), price number(3), no_copy number(4), PRIMARY KEY (isbn,auth_name), foreign key (isbn) references book_45, foreign key (auth_name) references author_45 );     insert into author_45 values ('Benoit','F',42,'French'); insert into author_ 45 values ('Antonini','M',33,'Italian'); insert into author_ 45 values ('McAven','F',31,'Australian'); insert into author_ 45 values ('Williams','M',90,'British');     insert into book_45 values (101,'atabases',1,'Possum'); insert into book_45 values (202,'SQL Primer',2,'Hall'); insert into book_45 values…

Consider the following table: Instructors ID 12121 15151 22222 32343 33456 name Alice Wu John Mozart Frank Einstein El Said Chelsea Dunn deptName Finances Music Physics History Physics salary 90000.00 40000.00 95000.00 60000.00 90000.00 Write a single SQL query to list in descending order the deptNames and names of all instructors. Note that every column of Instructors should be included in the result.

Express the following SQL code in Relational Algebra form.SELECT *FROM COURSEWHERE (COURSE.COLLEGE <> ’Business’OR COURSE.COLLEGE <> ’Engineering’)AND COURSE.CREDIT = ’U’;