Until now, we have basically learned how to insert, modify, or delete rows. We also used queries such as the following one to verify what we've written into the tables:
SELECT * FROM <table_name>;
This is the simplest query we could write: it simply reads all the columns and rows from a table. However, normally we only need to read a subset of columns and rows. We may also need to request some additional operations on the data we extract, such as ordering or grouping. The
SELECT statement is the most complex, and we will fully explore it in this section.
Specifying the table and column names
The basic syntax for
SELECT <expression_list> FROM <table_name>;
Until now, we have always used a n asterisk (
*) as an expression list. ...