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This article introduces the relevant knowledge of "how to use Salesforce statements to modify data". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

One. DML statement

DML is an action performed to insert, update, delete, rise, restore records, merge records, or convert leads.

DML is one of the most important parts of Apex because almost every business case involves changes and modifications to the database

SOQL is called Salesforce Object Query Language. Through the SOQL statement, you can operate the addition, deletion, modification and query of sObject.

Example:

Let's take the above Student table as an example.

The API Name of the Student table is Student__c, so in apex, as long as the corresponding DML operation is performed on the Student__c object, it is the operation on the Student data table.

Note: the apex code adds, deletes, modifies and queries the table by manipulating the table and the corresponding API Name of the column.

/ * sObject has two commonly used initialization methods, the first is the common new, and the second is new, which inserts parameters as constructor contents. Multiple parameters use','to separate * / Student__c student1 = new Student (Name__c='student1'); Student__c student2 = new Student (); student2.Name__c = 'student2'; / / add a student record-> insertinsert student1 / / SOQL is a simple way to add a record, which is the same as Database.insert (student1). For more information, see document insert student2;// modifying a student record-> updatestudent1.Name__c = 'student update';update student1;//SOQL modified record is easy to write, with Database.update (student1) / * adding or modifying a student record upsertupsert principle: upsert determines whether this record exists by whether it exists or not, 1. If this ID does not exist, then the insert operation is performed; 2. If there is and there is only one ID, the update operation is performed; 3. If there is an ID and there are multiple ID, DMLException*/// is thrown. When the insert statement is executed above, the Id is assigned to the student1, so the following code executes the update operation student1.Name__c = 'student upsert';upsert student1;//SOQL', which is the same as Database.upsert (student1); / / delete a student record deletedelete student2;//SOQL, which is the same as Database.delete (student2) Note: DMLException can occur during DML operations, so it is best to do try,catch processing when performing DML operations. Eg:try {insert student1;} catch (DMLException e) {/ / TODO} finally {/ / TODO}

The query statement returns List data, and the query statement can also carry out corresponding complex processing, such as where query, include,exclude,limit and so on. There are too many contents in this part. This article only deals with the most basic query operations. Later, we will discuss in detail the details of SOQL statements and queries associated with multiple tables.

Where statements are often accompanied by parameter passing, such as querying the number of students whose names are zhangsan, etc., if you use string, it is easy to cause errors, and the code is not easy to read. Apex provides a convenient way to declare variables used in query statements using the': 'symbol, similar to PreparedStatement in Java.

There are two ways to query, one is through [select.] Way to query, which is not conducive to the expansion of SQL statements, so this way is not recommended

The second way is to construct the query string and retrieve the data through the Database.query (queryString) method, which is flexible and scalable, so it is recommended.

Also note: in the Force.com platform database, the query cannot use the'* 'symbol to represent all the fields of the query, if all the fields of the query need to be listed.

This is the end of the content of "how to use DML statements to modify data in Salesforce". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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