Summary  
This chapter explains how to execute SQL commands in C# using MySqlCommand methods—ExecuteNonQuery for non-query operations, ExecuteReader to iterate over query results with a MySqlDataReader, and ExecuteScalar for retrieving single values—while constructing and formatting the SQL in code.  

General domain of usage  
Relational database access

> 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.

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?

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?

This course will give you a solid foundation to begin making applications using .NET in C#. Covering console applications, asynchronous programming, web services, database fundamentals, and ADO.NET CRUD operations, you'll gain practical skills. From creating apps and handling exceptions to optimizing database access, this course ensures a robust understanding of essential .NET development concepts.

This module will give you a solid foundation to begin making applications using .NET in C#. Covering console applications, asynchronous programming, web services, database fundamentals, and ADO.NET CRUD operations, you'll gain practical skills. From creating apps and handling exceptions to optimizing database access, this course ensures a robust understanding of essential .NET development concepts.

MySqlCommand Methods

Important Points

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?