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Introduction to .NET with C#

MySqlCommand MethodsMySqlCommand Methods

Note

If you're unable to delete objects from the MySQL server, it is possible that the server is running in safe mode. To disable safe mode, you can run the following query: SET SQL_SAFE_UPDATES=0;.

Important Points

  • We use ExecuteNonQuery for commands which modify the database;
  • ExecuteReader and ExecuteScalar are for querying commands that retrieve data from the database;
  • ExecuteReader returns a MySqlDataReader object;
  • MySqlDataReader has a method called read() which reads the rows in a sequential manner; We need to Close() the MySqlDataReader object after use;
  • ExecuteScalar returns an object which can be type-casted into the appropriate data type.
1. The following command selects and returns all the students that have marks higher than 90, which command is the most appropriate for executing this query?
2. The following command selects and returns the name of the oldest student in the class, which command is the most appropriate for executing this query?

The following command selects and returns all the students that have marks higher than 90, which command is the most appropriate for executing this query?

Виберіть правильну відповідь

The following command selects and returns the name of the oldest student in the class, which command is the most appropriate for executing this query?

Виберіть правильну відповідь

Все було зрозуміло?

Секція 3. Розділ 8
course content

Зміст курсу

Introduction to .NET with C#

1. Introduction

What is the .NET Platform exactly?Creating a Console ApplicationTaking input from the UserTask - Building a Simple CalculatorDealing with Exceptions caused by User InputTask - Improving the CalculatorReading FilesWriting FilesTask - File Based Calculator

2. Asynchronous Programming and Introduction to Web Services

What is Asynchronous Programming?Implementing an Asynchronous MethodTask - Asynchronously Reading FilesIntroduction to APIsMaking a GET RequestTask - Using an APIHandling Exceptions caused by HTTP RequestTask - Exception Handling for API Response

3. Introduction to Databases with .NET

What is a Database?Structure of a Relational DatabaseSetting Up A MySQL ServerConnecting to the MySQL ServerTask - Writing Connection StringsExecuting CommandsTask - Executing MySQL CommandsMySqlCommand MethodsTask - Connecting to a MySQL Database and Executing Commands

4. CRUD Operations with MySQL

Introduction to CRUD OperationsInstalling & Using MySQL WorkbenchCREATE - Part ITask - Using CREATECREATE - Part IITask - Using INSERTReadTask - Using SELECTUpdateTask - Using UPDATEDelete - Part IDelete - Part IITask - Using DELETE

5. Optimizing Database Operations

Stored ProceduresTask - Executing Stored ProceduresDataReader vs DataSetDataAdapter & DataSetTask - Reading Tables using MySqlDataAdapterWhat's Next?

Introduction to .NET with C#

MySqlCommand MethodsMySqlCommand Methods

Note

If you're unable to delete objects from the MySQL server, it is possible that the server is running in safe mode. To disable safe mode, you can run the following query: SET SQL_SAFE_UPDATES=0;.

Important Points

  • We use ExecuteNonQuery for commands which modify the database;
  • ExecuteReader and ExecuteScalar are for querying commands that retrieve data from the database;
  • ExecuteReader returns a MySqlDataReader object;
  • MySqlDataReader has a method called read() which reads the rows in a sequential manner; We need to Close() the MySqlDataReader object after use;
  • ExecuteScalar returns an object which can be type-casted into the appropriate data type.
1. The following command selects and returns all the students that have marks higher than 90, which command is the most appropriate for executing this query?
2. The following command selects and returns the name of the oldest student in the class, which command is the most appropriate for executing this query?

The following command selects and returns all the students that have marks higher than 90, which command is the most appropriate for executing this query?

Виберіть правильну відповідь

The following command selects and returns the name of the oldest student in the class, which command is the most appropriate for executing this query?

Виберіть правильну відповідь

Все було зрозуміло?

Секція 3. Розділ 8
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