How does linq execute SQL statements?

In LINQ, you can execute SQL statements in two ways: using LINQ to SQL or using Entity Framework.

The steps to executing SQL statements using LINQ to SQL are as follows:

1. Context of the data

using (var context = new DataContext(connectionString))
{
    // 执行SQL语句
}

1. Create SQL query: Use LINQ query expressions or method chaining to create SQL queries.

Example of using LINQ query expressions:

var query = from c in context.Customers
            where c.City == "London"
            select c;

Example of using method chaining:

var query = context.Customers.Where(c => c.City == "London");

1. Convert to a list
2. Return the first element of a sequence, or a default value if the sequence is empty.

var result = query.ToList();

Full example:

using (var context = new DataContext(connectionString))
{
    var query = from c in context.Customers
                where c.City == "London"
                select c;

    var result = query.ToList();
}

The steps for executing SQL statements using Entity Framework are as follows:

1. Context of database operations

using (var context = new DbContext(connectionString))
{
    // 执行SQL语句
}

1. Create a SQL query: Use LINQ query expressions or method chaining to create a SQL query.

An example of using LINQ query expressions:

var query = from c in context.Customers
            where c.City == "London"
            select c;

Example of using method chaining:

var query = context.Customers.Where(c => c.City == "London");

1. Convert to a list.
2. Return the first element or a default value if the sequence is empty.

var result = query.ToList();

Full example:

using (var context = new DbContext(connectionString))
{
    var query = from c in context.Customers
                where c.City == "London"
                select c;

    var result = query.ToList();
}

It is important to note that when executing SQL statements using LINQ to SQL or Entity Framework, queries can be created using query expressions or method chaining, and results can be retrieved using methods like ToList(), FirstOrDefault(), etc. Additionally, other LINQ operators like OrderBy(), GroupBy(), etc. can also be used to sort, group, and manipulate the query results.