Apex SOQL 查詢中的潛在異常情況

分配給單個物件時，返回除單行之外的任何內容的查詢將丟擲 QueryException。

try {
    Account a = [SELECT Id FROM Account WHERE Name = 'Non-existent Account'];  
} catch (QueryException e) {
    // List has no rows for assignment to SObject
}

try {
    Account a = [SELECT Id FROM Account];  
} catch (QueryException e) {
    // List has more than 1 row for assignment to SObject
}

嘗試使用你未在查詢中包含的欄位將丟擲 SObjectException

Account a = [SELECT Id FROM Account LIMIT 1];
try {
    System.debug( a.Name );
} catch (SObjectException e) {
    // SObject row was retrieved via SOQL without querying the requested field: Name
}