Sql queries to correct mistakes

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SQL

Some queries of update and delete, Some are completed and some are left to be complete, which i don't understand, please help me to correct mistakes if there any.Thanks

Insert new employee’s records having empno 123 and name Ronaldo
Ans) insert into emp(empno and name) values(123,Ronaldo);


Delete the records of Sales department
Ans) Delete from salesdepart;

Change the employees address for Smith
Ans)


Update the salary of each employee to 5000.
Ans) Update emp set salary= sal+5000;

Change the Mgr of each employee 7934.
Ans)

Change the commission of department 20 to 1000.

Ans)
Change the hiredate of all clerk to 02-04-2000.
Ans) Update emp set hiredate= 02-04-2000 where job="Clerk";
Change the hiredate of all salesman to 02-March-99 where department no is 30.
Ans)
Update the salary of each employee whose name start with ‘A’.
Ans)
Delete all the records having deptno 20.
Ans) Delete from emp where deptno=20;

Delete all records where salary is greater than 2000.
Ans) Delete from emp where salary > 2000;