Remember to print out the following definitions and keep them by your desk in case you forget what a complex right inner join is:
Don't use joins
Joins become a problem with Oracle and SQL Server DBMSs because the two systems have fundamentally different approaches to the concept. Basically, joins don’t always work the same on every DBMS, and you can end up with unexpected result sets. Before we talk about the differences and how to get around them, you should understand the basic types of join clauses:
The important thing to remember about joins is to not use them if you want your application to work well with different database servers.
Joins are powerful SQL commands for creating tables from data that is retrieved from multiple sources.
Equi-Joins are formed by retrieving all the data from two separate sources and combining it into one, large table.
- Inner/Outer Join
Inner Joins are joined on the inner columns of two tables. Outer Joins are joined on the outer columns of two tables.
- Left/Right Join
Left Joins are joined on the left columns of two tables. Right Joins are joined on the right columns of two tables.
- Compound/Complex Joins
There are also other kinds of joins—left/inner, left/outer, right/inner, and right/outer.
I love the way that it's exactly the kind of thing you would make up, if you were 12 and had absolutely no idea how to answer a homework question.
While I'm at it I can't help quoting a bit more, this time about the well-known ADD command:
From the article "Database design for platform independence", TechRepublic 2002.
ANSI SQL: CREATE, DROP, ADD, UPDATE, DELETE, INSERT, SELECT
As a rule, the only commands you should use are:
- CREATE and DROP for Data Definition Language (DDL).
- ADD, UPDATE, DELETE and INSERT for Data Manipulation Language (DML).
- SELECT for data retrieval.