Using Aliases with Simple Subqueries : alias column « Select Query « Oracle PL / SQL






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

Using Aliases with Simple Subqueries

 
SQL>
SQL>
SQL> CREATE TABLE dept (
  2     deptID INT NOT NULL PRIMARY KEY,
  3     empID    INT NOT NULL,
  4     ClassID      INT NOT NULL,
  5     EnrolledOn   DATE,
  6     Grade        INT);

Table created.

SQL>
SQL> INSERT INTO dept (deptID,empID,ClassID,EnrolledOn,Grade) VALUES (1,1,1,DATE '2002-09-23',62);

1 row created.

SQL> INSERT INTO dept (deptID,empID,ClassID,EnrolledOn,Grade) VALUES (2,1,2,DATE '2002-09-30',70);

1 row created.

SQL> INSERT INTO dept (deptID,empID,ClassID,EnrolledOn,Grade) VALUES (3,2,3,DATE '2003-09-23',51);

1 row created.

SQL> INSERT INTO dept (deptID,empID,ClassID,EnrolledOn,Grade) VALUES (4,2,5,DATE '2003-09-23',41);

1 row created.

SQL> INSERT INTO dept (deptID,empID,ClassID,EnrolledOn,Grade) VALUES (5,2,6,DATE '2003-09-23',68);

1 row created.

SQL> INSERT INTO dept (deptID,empID,ClassID,EnrolledOn,Grade) VALUES (6,3,4,DATE '2002-09-30',78);

1 row created.

SQL>
SQL>
SQL> SELECT e1.empID, e1.ClassID, (
  2     SELECT COUNT(*) FROM dept e2
  3     WHERE e1.ClassID = e2.ClassID)-1
  4     AS OtherempsInClass
  5  FROM dept e1
  6  WHERE empID = 6;

no rows selected

SQL>
SQL> drop table dept;

Table dropped.








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