(one) Oracle New notes------SET operation __oracle

Set operator precedence is the same as "="

Union: joint operation (combined with set, going heavy)

Query number 7833 current wages, positions and historical wages, jobs

SELECT sal,job from EMP WHERE empno=7839

UNION

SELECT sal,job from Emp_jobhistory WHERE empno=7839

UnionAll: Full union operation (and set, not heavy)

SELECT sal,job from EMP WHERE empno=7839

UNION All

SELECT sal,job from Emp_jobhistory WHERE empno=7839

INTERSECT: Intersecting operations (intersection)

SELECT empno from EMP

INTERSECT

SELECT empno from Emp_jobhistory;

minus: subtracting operations (difference sets)

SELECT empno from EMP

Minus

SELECT empno from Emp_jobhistory;