Learn SQL Database Programming

Understanding the different ways to query with a SELECT statement

Generally, you should select the minimum amount of data that you need from a table. When selecting data from a table, you can retrieve a single column, multiple columns, or all columns.

Avoid using SELECT * in a query. Since this selects all columns in a table, it is considered more expensive than if you specify the columns you need. Expensive means that it takes more server resources to return your query results, and when you have many queries executing on a server, you want them to use the minimum resources required.

To retrieve data from just one column, execute the following query:

SELECT playerid FROM lahmansbaseballdb.appearances;

The preceding query will give the ...