Support EXCEPT/INTERSECT Operators

[scsldb]

Description

Support EXCEPT/INTERSECT Operators, Returns distinct rows by comparing the results of two queries.

• EXCEPT returns distinct rows from the left input query that aren't output by the right input query.
• INTERSECT returns distinct rows that are output by both the left and right input queries operator.
• To combine the result sets of two queries that use EXCEPT or INTERSECT, the basic rules are:
  • The number and the order of the columns must be the same in all queries.
  • The data types must be compatible

Category

Feature

Value

A common feature in analytics.

Time

GanttStart: 2020-07-03
GanttDue: 2020-07-24
GanttProgress: 90%

Progress Tracking

Project Link

[lzmhhh123]

The performance of null computing in ms sql-server:

mssql> create table t(a int);
OK

Executed in 0 ms
mssql> insert into t values(1),(2),(null),(3);
OK

Executed in 0 ms
mssql> select * from t intersect select null;
a
----
null

1 row(s) returned

Executed in 1 ms
mssql> select * from t except select null;
a
-
1
2
3

3 row(s) returned