Nested Multi-Table Equi-Joins : Table Join Basics « Table Joins « Oracle PL / SQL

1. Oracle PL / SQL
2. Table Joins
3. Table Join Basics

Nested Multi-Table Equi-Joins

   
SQL>
SQL>
SQL> CREATE TABLE empExam (
  2     empID  INT NOT NULL,
  3     ExamID     INT NOT NULL,
  4     Mark       INT,
  5     Taken   SMALLINT,
  6     Comments   VARCHAR(255),
  7     CONSTRAINT PK_empExam PRIMARY KEY (empID, ExamID));

Table created.

SQL>
SQL>
SQL> INSERT INTO empExam (empID,ExamID,Mark,Taken,Comments) VALUES (1,1,55,1,'Satisfactory');

1 row created.

SQL> INSERT INTO empExam (empID,ExamID,Mark,Taken,Comments) VALUES (1,2,73,1,'Good result');

1 row created.

SQL> INSERT INTO empExam (empID,ExamID,Mark,Taken,Comments) VALUES (2,3,44,1,'Hard');

1 row created.

SQL> INSERT INTO empExam (empID,ExamID,Mark,Taken,Comments) VALUES (2,5,39,0,'Simple');

1 row created.

SQL> INSERT INTO empExam (empID,ExamID,Mark,Taken) VALUES (2,6,63,1);

1 row created.

SQL>
SQL>
SQL> CREATE TABLE Exam (
  2     ExamID      INT NOT NULL PRIMARY KEY,
  3     CourseID    INT NOT NULL,
  4     InstructorID INT NOT NULL,
  5     SustainedOn DATE,
  6     Comments    VARCHAR(255));

SQL>
SQL> CREATE TABLE emp (
  2     empID INT NOT NULL PRIMARY KEY,
  3     Name      VARCHAR(50) NOT NULL);

Table created.

SQL> INSERT INTO emp (empID,Name) VALUES (1,'Tom');

1 row created.

SQL> INSERT INTO emp (empID,Name) VALUES (2,'Jack');

1 row created.

SQL> INSERT INTO emp (empID,Name) VALUES (3,'Mary');

1 row created.

SQL> INSERT INTO emp (empID,Name) VALUES (4,'Bill');

1 row created.

SQL> INSERT INTO emp (empID,Name) VALUES (5,'Cat');

1 row created.

SQL> INSERT INTO emp (empID,Name) VALUES (6,'Victor');

1 row created.

SQL>
SQL> SELECT empExam.ExamID,
  2         empExam.Mark,
  3         Exam.SustainedOn,
  4         emp.Name
  5  FROM Exam
  6     INNER JOIN (emp
  7        INNER JOIN empExam ON emp.empID = empExam.empID)
  8     ON Exam.ExamID = empExam.ExamID
  9  ORDER BY empExam.ExamID;

    EXAMID       MARK SUSTAINED
---------- ---------- ---------
NAME
--------------------------------------------------
         1         55 12-MAR-03
Tom

         2         73 13-MAR-03
Tom

         3         44 11-MAR-03
Jack

         5         39 19-MAR-03
Jack


4 rows selected.

SQL>
SQL>
SQL> drop table emp;

Table dropped.

SQL> drop table empExam;

Table dropped.

SQL> drop table exam;

Table dropped.

   
    
    
  

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