SOQL Naming Conventions
SELECT statements are used to fetch data from Salesforce by specifying which fields we want to retrieve. In addition to the fields we want to bring, we also have to tell Salesforce which Object to get. To do this we use the keyword
FROM followed by the name of the Object.
For example, if we want to see some records in the Contact Object, we could use the following query:
Note that only MRN (medical representative number) is written as MRN__c, meaning it is a custom field on a standard object. Id, FirstName, Lastname are standard fields and can not be appended with __c.
Now let’s take a look at SOQL on a custom object
Note that Id, Name is a standard field created automatically for all custom objects and cannot be appended by __c. Custom fields and Custom objects are appended with __c.
The logical_expressions which combine multiple logical operators must use parentheses to declare priority of one operator over the other. Otherwise, a syntax error is shown.
Example: Find the clinics which are either in zip code 32003 or 32004, and open on holidays.
SOQL Order of execution
The SOQL order of execution defines the order in which the clauses of a query are evaluated. Some of the most common query challenges I run into could be easily avoided with a clearer understanding of the SOQL order of execution.
- GROUP BY
- ORDER BY