Using Aliasing in Equi-Joins : alias column « Select Query « Oracle PL / SQL

1. Oracle PL / SQL
2. Select Query
3. alias column

Using Aliasing in Equi-Joins

 
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> 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>
SQL> SELECT SE.ExamID,
  2         SE.Mark,
  3         S.Name AS empName
  4  FROM empExam AS SE
  5     JOIN emp AS S
  6     ON SE.empID = S.empID
  7  ORDER BY ExamID
  8
SQL>
SQL>
SQL> drop table emp;

Table dropped.

SQL> drop table empexam;

Table dropped.

   
  

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