How to Properly Close a SqlDataReader in C#?

Closing a SqlDataReader correctly prevents memory leaks, connection issues, and unclosed resources. Here’s the best way to do it.

Use 'using' to Auto-Close

Using using statements ensures SqlDataReader and SqlConnection are closed even if an exception occurs.

Example

using (SqlConnection conn = new SqlConnection(connectionString))
{
    conn.Open();
    using (SqlCommand cmd = new SqlCommand("SELECT * FROM Users", conn))
    using (SqlDataReader reader = cmd.ExecuteReader())
    {
        while (reader.Read())
        {
            Console.WriteLine(reader["Username"]);
        }
    } // ✅ Auto-closes reader here
} // ✅ Auto-closes connection here

This approach auto-closes resources when done and it is cleaner and less error-prone than manual closing.

⚡ Alternative: Manually Close in finally Block

If you need explicit control, you can manually close it inside a finally block.

SqlDataReader? reader = null;
try
{
    using SqlConnection conn = new SqlConnection(connectionString);
    conn.Open();
    using SqlCommand cmd = new SqlCommand("SELECT * FROM Users", conn);
    reader = cmd.ExecuteReader();

    while (reader.Read())
    {
        Console.WriteLine(reader["Username"]);
    }
}
finally
{
    reader?.Close();  // ✅ Closes reader if it was opened
}

This is slightly more error prone if you forget to add a finally block. But might make sense when you need to handle the reader separately from the command or connection.

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Related

Measuring the execution time of C# methods is essential for performance optimization and identifying bottlenecks in your application.

The most straightforward approach uses the Stopwatch class from the System.Diagnostics namespace, which provides high-precision timing capabilities.

This approach is perfect for quick performance checks during development or when troubleshooting specific methods in production code.

Here's a practical example: Imagine you have a method that processes a large dataset and you want to measure its performance.

First, add using System.Diagnostics; to your imports. Then implement timing as shown below:

public void MeasurePerformance()
{
    Stopwatch stopwatch = new Stopwatch();
    
    // Start timing
    stopwatch.Start();
    
    // Call the method you want to measure
    ProcessLargeDataset();
    
    // Stop timing
    stopwatch.Stop();
    
    // Get the elapsed time
    Console.WriteLine($"Processing time: {stopwatch.ElapsedMilliseconds} ms");
    // Or use ElapsedTicks for higher precision
    Console.WriteLine($"Processing ticks: {stopwatch.ElapsedTicks}");
}

For more advanced scenarios, consider using the BenchmarkDotNet library, which offers comprehensive benchmarking with statistical analysis.

Simply install the NuGet package, decorate methods with the [Benchmark] attribute, and run BenchmarkRunner.Run<YourBenchmarkClass>() to generate detailed reports comparing different implementation strategies.

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React's rendering process is powerful but can become inefficient when components re-render without meaningful changes.

Let's explore strategies to prevent these unnecessary renders.

Understanding the Problem

React components typically re-render in three scenarios:

  • If the state changes
  • If the props change
  • Parent component re-renders

The last scenario can lead to wasted renders when child components don't actually need updating:

Let's take a look at an example of this scenario:

function ParentComponent() {
  const [count, setCount] = useState(0);
  
  return (
    <div>
      <button onClick={() => setCount(count + 1)}>
        Clicked {count} times
      </button>
      <ChildComponent /> {/* Re-renders on every click despite no prop changes */}
    </div>
  );
}

React.memo for Function Components

Wrap function components with React.memo() to skip renders when props haven't changed:

const ChildComponent = React.memo(function ChildComponent() {
  console.log("Child rendered!");
  return <div>I'm a memoized component</div>;
});

// Now ChildComponent only re-renders when its props change

shouldComponentUpdate for Class Components

For class components, implement shouldComponentUpdate():

class ListItem extends React.Component {
  shouldComponentUpdate(nextProps) {
    // Only re-render if the item data changed
    return nextProps.item.id !== this.props.item.id || 
           nextProps.item.content !== this.props.item.content;
  }
  
  render() {
    return <div>{this.props.item.content}</div>;
  }
}

useMemo and useCallback Hooks

Prevent recreating objects and functions on each render:

function SearchComponent({ data }) {
  const [query, setQuery] = useState("");
  
  // Without useMemo, filteredData would be recalculated on every render
  const filteredData = useMemo(() => {
    return data.filter(item => item.name.includes(query));
  }, [data, query]); // Only recalculate when data or query changes
  
  // Prevent handleClick from being recreated on every render
  const handleClick = useCallback(() => {
    console.log("Button clicked!");
  }, []); // Empty dependency array means this function never changes
  
  return (
    <div>
      <input value={query} onChange={e => setQuery(e.target.value)} />
      <button onClick={handleClick}>Search</button>
      <DataList data={filteredData} />
    </div>
  );
}

By implementing these techniques, you'll significantly reduce unnecessary renders and improve your React application's performance!

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Raw string literals in C# provide a flexible way to work with multiline strings, with some interesting rules around how quotes work.

The key insight is that you can use any number of double quotes (three or more) to delimit your string, as long as the opening and closing sequences have the same number of quotes.

The Basic Rules

  1. You must use at least three double quotes (""") to start and end a raw string literal
  2. The opening and closing quotes must have the same count
  3. The closing quotes must be on their own line for proper indentation
  4. If your string content contains a sequence of double quotes, you need to use more quotes in your delimiter than the longest sequence in your content

Examples with Different Quote Counts

// Three quotes - most common usage
string basic = """
    This is a basic
    multiline string
    """;

// Four quotes - when your content has three quotes
string withThreeQuotes = """"
    Here's some text with """quoted""" content
    """";

// Five quotes - when your content has four quotes
string withFourQuotes = """""
    Here's text with """"nested"""" quotes
    """"";

// Six quotes - for even more complex scenarios
string withFiveQuotes = """"""
    Look at these """""nested""""" quotes!
    """""";

The N+1 Rule

The general rule is that if your string content contains N consecutive double quotes, you need to wrap the entire string with at least N+1 quotes. This ensures the compiler can properly distinguish between your content and the string's delimiters.

// Example demonstrating the N+1 rule
string example1 = """
    No quotes inside
    """; // 3 quotes is fine

string example2 = """"
    Contains """three quotes"""
    """"; // Needs 4 quotes (3+1)

string example3 = """""
    Has """"four quotes""""
    """""; // Needs 5 quotes (4+1)

Practical Tips

  • Start with three quotes (""") as your default
  • Only increase the quote count when you actually need to embed quote sequences in your content
  • The closing quotes must be on their own line and should line up with the indentation you want
  • Any whitespace to the left of the closing quotes defines the baseline indentation
// Indentation example
string properlyIndented = """
    {
        "property": "value",
        "nested": {
            "deeper": "content"
        }
    }
    """; // This line's position determines the indentation

This flexibility with quote counts makes raw string literals extremely versatile, especially when dealing with content that itself contains quotes, like JSON, XML, or other structured text formats.

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