How to select data from a table, including records with zero values in certain fields?

To select data from a table, including records with zero values in certain fields, in SQL you need to use a condition that accounts for NULL and zero values. For example, if you want to select all records where the amount field is 0 or NULL, the query would be:

SELECT * FROM table_name
WHERE amount = 0 OR amount IS NULL;

In PHP, if you are using PDO or mysqli for fetching, simply execute such a query and process the result. It is important to remember that NULL cannot be compared with =, for this IS NULL is used.

If you want to select all records, including those where the field can be NULL or 0, the condition should explicitly account for this.