5.11One major difference from SQL

Don't instinctively write:

SELECT *
FROM Account

SOQL does not use ordinary SQL-style * to select everything. Salesforce supports explicit field lists and, in supported contexts, constructs such as FIELDS(ALL).

In integration code, explicit fields are usually better anyway:

SELECT
    Id,
    Name,
    Phone,
    External_Customer_ID__c
FROM Account

Why?

less data
clear contract
less accidental exposure
better stability