A few sql guys help me take a look

First of all, you have a problem in the title, that is, the first one should be the department table, I assume it is called d emp.

Question A Answer:

select t_ from t_emp,d_emp where d_'A piece of software' and t_。

Explain this sentence: Where do you find the employee's name first? What are the conditions for finding from the two tables of t emp and d emp?

The condition is d'A piece of software', that is, the department is a part of the software, and the last sentence is to connect the two tables and connect them by the department number.

Question B Answer:

insert into t_emp(emp_id dept_id emp_name) values (888,111,'Xiao Li')。

Question C Answer:

I really forgot about this, I forgot how to display it in a tree structure, and this seems to depend on what database you're using.

Define the name of the first department table as d emp

The second employee form T emp

A answer. select * from t_emp where dept_id in(002,003,004 )

B answer. insert into t_emp (emp_id,dept_id,emp_name) values ('888','111','Xiao Li')

insert into d_emp(dept_id,p_deptid,dept_name)values('111','001','111 Division')

C answer. -Firm.

select * from d_emp where p_deptid =0

All departments under the company.

select * from d_emp where p_deptid =001

All subordinate departments under each department.

select * from d_emp where dept_id in(select p_deptid from d_emp where p_deptid =001)

The table is wrong, right? Suppose the following table is available:

t dep --departmental table).

t emp -- staff table) then :

a : select emp_name from t_emp where dept_id = '002'

or : select emp name from t emp where dept id in (select dept id from t dep where dept name =.)'A piece of software')

b : insert into t_dep(dept_id p_deptid dept_name) values ('111','001','111 Division

insert into t_emp(emp_id dept_id emp_name) values ('888','111','Xiao Li')

C : Select Company A, dept name from t dep where p deptid like'0%'

table emp

eno varchar(20)，ename varchar(20)，salary varchar(20)，dno varchar(20) )

create table emp

dno varchar(20)，dname varchar(20)，manager varchar(20) )

How are the 2 table names the same?

Question 1: Suppose the first one is Table A and the second one is B

select b.* from b join a on where '002'