Oracle collection Query

For Oracle set query, the Orderby clause can only appear in the last statement. The column name or alias accepted by the first select statement

For Oracle set query, the Order by clause can only appear in the last statement. The column name or alias accepted by the first select statement

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Oracle collection Query

[Date: 2012-03-14] Source: Linux Author: java958199586 [Font:]

Union

Select * from emp where deptno = 10 union select * from emp where deptno = 20;

Select * from emp where deptno = 10 union all select * from emp where deptno = 20;

Select * from emp where ename like '% A %' or ename like '% M % ';

Select * from emp where ename like '% A %' union ename like '% M %'; // remove all parts

Select * from emp where ename like '% A %' union all ename like '% M %'; // do not remove

Intersection

Select * from emp where ename like '% A %' intersect ename like '% M %'; // common parts

Difference set

Belongs to first, not belongs to second

The Order by clause can only appear in the last statement. The column name or alias accepted by the first select statement

The column name of the query result must be the same as the column name of the first select statement.

Select * from (select * from emp where sal between 700 and 1300 union select * from emp where sal between 1200 and 1400) order by sal desc;

Select ename, sal from emp where sal between 700 adn 1300 union select ename, sal from emp where sal between 1200 and 1400 order by sal deces;

In the select statement, the parameter types and numbers must be consistent.

Brackets can be used to change the sequence of execution of the set.

The set operation uses the header of the first statement as the header.

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