Salesforce SOQL describe table

Question

Is there a way to fetch a list of all fields in a table in Salesforce? DESCRIBE myTable doesn't work, and SELECT * FROM myTable doesn't work.

Answer 1

From within Apex, you can get this by running the following Apex code snippet. If your table/object is named MyObject__c, then this will give you a Set of the API names of all fields on that object that you have access to (this is important --- even as a System Administrator, if certain fields on your table/object are not visible through Field Level Security to you, they will not show up here):

// Get a map of all fields available to you on the MyObject__c table/object
// keyed by the API name of each field
Map<String,Schema.SObjectField> myObjectFields 
   = MyObject__c.SObjectType.getDescribe().fields.getMap();

// Get a Set of the field names
Set<String> myObjectFieldAPINames = myObjectFields.keyset();

// Print out the names to the debug log
 String allFields = 'ALL ACCESSIBLE FIELDS on MyObject__c:\n\n';
for (String s : myObjectFieldAPINames) {
    allFields += s + '\n';
}
System.debug(allFields);

To finish this off, and achieve SELECT * FROM MYTABLE functionality, you would need to construct a dynamic SOQL query using these fields:

List<String> fieldsList = new List<String>(myObjectFieldAPINames);
String query = 'SELECT ';
// Add in all but the last field, comma-separated
for (Integer i = 0; i < fieldsList.size()-1; i++) {
   query += fieldsList + ',';
}
// Add in the final field
query += fieldsList[fieldsList.size()-1];
// Complete the query
query += ' FROM MyCustomObject__c';
// Perform the query (perform the SELECT *)
List<SObject> results = Database.query(query);