EXCEPT (MINUS) for differences in SQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the SQL EXCEPT operator do?

The EXCEPT operator returns rows from the first query that are not present in the second query. It shows the difference between two result sets.

beginner

How is EXCEPT different from UNION in SQL?

UNION combines rows from two queries, removing duplicates, while EXCEPT returns only rows from the first query that do not appear in the second.

intermediate

Which SQL keyword is equivalent to EXCEPT in some databases like Oracle?

MINUS is equivalent to EXCEPT in Oracle and some other databases. Both return the difference between two queries.

intermediate

Can EXCEPT be used with queries that return different columns?

No, both queries must return the same number of columns with compatible data types for EXCEPT to work.

beginner

What happens if you use EXCEPT and the second query returns rows not in the first query?

Those rows are ignored because EXCEPT only returns rows from the first query that are missing in the second.

What does the EXCEPT operator return in SQL?

A Rows in the first query but not in the second

B Rows common to both queries

C All rows from both queries combined

D Rows in the second query but not in the first

EXCEPT returns rows from the first query that do not appear in the second query.

Which SQL keyword is similar to EXCEPT in Oracle?

A MINUS

B UNION

C INTERSECT

D JOIN

MINUS in Oracle works like EXCEPT, showing rows in the first query not in the second.

What must be true about the columns in queries used with EXCEPT?

A Columns must be named the same

B They can have different numbers of columns

C They must have the same number and compatible data types

D Only the first column must match

Both queries must return the same number of columns with compatible types for EXCEPT to work.

If the second query returns rows not in the first, what does EXCEPT return?

A Those rows only

B All rows from both queries

C No rows

D Rows from the first query missing in the second

EXCEPT returns only rows from the first query that are missing in the second.

Which of these is NOT a set operation in SQL?

A MINUS

B SELECT

C UNION

D EXCEPT

SELECT is a basic query, not a set operation like EXCEPT, MINUS, or UNION.

Explain how the EXCEPT operator works in SQL and when you might use it.

Think about comparing two lists and finding what is unique to the first.

Describe the difference between EXCEPT and UNION in SQL.

One combines, the other subtracts.