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C# – SQL – Bulk Insert records from Data Table and CSV
In my previous article I provided the steps to update records in single transaction using SQL “Table-Valued Parameter Types”.
In this article, lets see an easy way to bulk insert the records using SQLBulkCopy
What is SQLBulkCopy:
- SQLBulkCopy class comes with ‘System.Data’ namespace and can be used to write/Insert data to SQL Server tables.
- Though there are other ways to load data into a SQL Server table (i.e., INSERT statements, for example) but ‘SQLBulkCopy’ offers a significant performance advantage.
Below are the steps to use SQLBulkCopy with the combination of ‘Data Table’
Steps:
To simplify the explanation, I am taking a ‘Student’ table with 3 columns.
- Create a ‘Student’ table.
- In C# console application, prepare a ‘Data Table’ with the structure similar to ‘Student’ SQL table.
tableStudents = new DataTable(“Student”);
tableStudents.Columns.Add(“StudentID”, typeof(string));
tableStudents.Columns.Add(“StudentName”, typeof(string));
tableStudents.Columns.Add(“City”, typeof(string));// Add ‘Student’ data as Rows to the Data Table
DataRow rowStudent = tableStudents.NewRow();
rowStudent[“StudentID”] = “RJ001”
rowStudent[“StudentName”] = “Rajeev”;
rowStudent[“City”] = “Hyd”;//Add the Data Row to Table
tableStudents.Rows.Add(rowStudent);
- Instantiate and execute the ‘SQLBulkCopy’ by passing the Data Table
using (SqlBulkCopy bulkCopy = new SqlBulkCopy({SQLConnection}, SqlBulkCopyOptions.TableLock | SqlBulkCopyOptions.FireTriggers | SqlBulkCopyOptions.UseInternalTransaction, null))
{
bulkCopy.DestinationTableName = “Student“; // Your SQL Table name//Optional mappings. Not required, if your ‘Data Table’ column names match with ‘SQL Table’ column names
bulkCopy.ColumnMappings.Add(“StudentID”, “StudentID”);
bulkCopy.ColumnMappings.Add(“StudentName”, “StudentName”);
bulkCopy.ColumnMappings.Add(“City”, “City”);
bulkCopy.WriteToServer(tableStudents);
isSuccuss = true;
}
- Execute the code which inserts rows from ‘Data Table’ to ‘Student’ SQL table.
Now lets see how to insert the CSV data to SQL table with query.
Note: You can also do the same with SQL Import Wizard
Bulk insert records from CSV to SQL Table:
- Assume that you have data available in a CSV file and want to insert them as records in SQL Table.
- Below is the query
Bulk Insert {SQL Table Name}
from ‘CSV File Path’
with
(rowterminator=’\n’,fieldterminator=’,’)
Stack overflow error while disposing object – C#
I have a class “ABC” which implements “IDisposable” interface and having below Dispose method.
Public Class ABC : IDisposable {
public void Dispose() {
this.Dispose(true);
}
}
When I run the application I was getting “Stack Overflow” error because the Dispose() method getting called recursively and went in to an infinite loop.
Fix :
- Prevent the Dispose() recursive call by using flag and the logic is as below
private bool disposed = false;
public void Dispose() {
this.Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing) {
if (this.disposed) {
return;
}
this.disposed = true;
}
🙂
XML to strongly typed object in C#
Assume you have composite XML and you want read the XML field values in your C# project, the simplest way is to convert in to Strongly type object and read as parameters.
It involves two steps as mentioned below
Generate XML Wrapper Class
- “Fruits.xml” is your XML file.
Composite XML
- Copy the XML file content.
- Open a new Class file “FruitsWrapper.cs” in Visual Studio 2012
- Select “EDIT -> Paste Special -> Paste XML As Classes”
Paste Special XML As Class
- Now you get XML wrapper class on your Class file
Generated XML Wrapper Class
- Save the file
Convert XML to Class
- To test the Conversion and read the XML data
- Take a console application and paste below code
static void Main(string[] args){
const string fruitsXmlPath = @”c:\Fruits.xml”;
// Set your Root Element Name (i.e., <Fruits> is the root node of our XML)
var xRoot = new XmlRootAttribute { ElementName = “Fruits”, IsNullable = true };
var xmlSerializer = new XmlSerializer(typeof(Fruits), xRoot);
var fruits = (Fruits)xmlSerializer.Deserialize(new FileStream(fruitsXmlPath, FileMode.Open));
// Read XML node values as Object Properties
Console.WriteLine(“Fruit Name” + fruits.CitrusFruits.Fruit.Name);
Console.WriteLine(“Fruit Price” + fruits.CitrusFruits.Fruit.Price);
}
This approach is useful when you have your application’s configuration details provided in an XML file and if the file is complex and big.
Note – If you don’t have “Paste Special -> Paste XML As Classes” feature in your Visual Studio, you can use XSD.exe tool to generate wrapper class from XML.
Reflection with method overloading C#
I have a class with 3 overloaded methods and when try to invoke method’s using Reflection, I was getting “Avoiding an ambiguous match exception” exception.
Below is the way to invoke overload methods using Reflection, which solved my exception.
Let’s take a class with 3 overload methods.
Class Structure
namespace MyNamespace{
public class CallMe{
public string MyName(){
return “You don’t have name”;
}
public string MyName(string firstName){
return “Your name is ” + firstName;
}
public string MyName(string firstName, string lastName){
return “Your name is ” + firstName + lastName;
}
}
Here is the way to invoke methods using Reflection
C# Code to call the Generic Method
// Load .dll
Assembly assembly = Assembly.LoadFile(“{Physical path of }MyNamespace.dll”);
// Set the Class type as “Namespace.Classname”
Type classType = assembly.GetType(“ReflectionClass.CallMe”);
// One of my methods expects 1 string hence creating MethodInfo object with 1 Type[] parameter
MethodInfo methodWithOneParameter = classType.GetMethod(“MyName”, new Type[] { typeof(string) });
// One of my methods expect 2 string parameters hence creating MethodInfo object with 2 Type[] parameters.
MethodInfo methodWithTwoParameter = classType.GetMethod(“MyName”, new Type[] { typeof(string), typeof(string) });
// To invoke overload with no parameters, provide an empty Type array to GetMethod’s second parameter
MethodInfo methodWithNoParameter = classType.GetMethod(“MyName”, new Type[0]);
// Invoke Methods
var resultMethodWithOneParameter = InvokeMethod(classType, methodWithOneParameter, new string[] { “Rajeev” });
var resultMethodWithTwoParameter = InvokeMethod(classType, methodWithTwoParameter, new string[] { “Rajeev”, “Pentyala” });
var resultMethodWithNoParameter = InvokeMethod(classType, methodWithNoParameter, null);
// Display Results
Console.WriteLine(“ResultMethodWithOneParameter – ” + resultMethodWithOneParameter.ToString());
Console.WriteLine(“ResultMethodWithTwoParameter – ” + resultMethodWithTwoParameter.ToString());
Console.WriteLine(“ResultMethodWithNoParameter – ” + resultMethodWithNoParameter.ToString());
C# Generic Method to Invoke methods
// Generic method Invokes methods and return Result as Object
public static object InvokeMethod(Type classType, MethodInfo methodInfo, object[] parametersArray){
object result = null;
if (classType != null) {
if (methodInfo != null) {
ParameterInfo[] parameters = methodInfo.GetParameters();
object classInstance = Activator.CreateInstance(classType, null);
if (parameters.Length == 0) {
//This works fine
result = methodInfo.Invoke(classInstance, null);
}
else {
//The invoke does NOT work it throws “Object does not match target type”
result = methodInfo.Invoke(classInstance, parametersArray);
}
}
}
return result;
}
We get the response as below
Reflection Overload Result
🙂
Separating alphabets and digits from Alphanumeric string– C#
We got a requirement to separate alphabets and digits from alphanumeric string as groups.
Let’s say my alphanumeric string is “Hel00Wor11DD” and I need to get
- Alphabet group as “Hel,Wor,DD”
- Digit group as “00,11”.
Below is the C# code which use Regular expressions and achieve the same
var digitGroup = newList<string>();
var alphabetGroup = newList<string>();
Match regexMatch = null;
string myString = “Hel00Wor11DD”;
while (myString.Length > 0){
if ((regexMatch = Regex.Match(myString, “\\d”)).Success){
// If myString is not starting with digit
if (regexMatch.Index > 0) {
alphabetGroup.Add(myString.Substring(0, regexMatch.Index));
}
// If myString is starting with digits but has subsequent alphabets
elseif ((regexMatch = Regex.Match(myString, “\\D”)).Success) {
digitGroup.Add(myString.Substring(0, regexMatch.Index));
}
// If myString only has digits, no more alphabets
else{
digitGroup.Add(myString.Substring(0));
// No more alphabets
break;
}
myString = myString.Substring(regexMatch.Index);
}
// There are no digits in myString
else{
alphabetGroup.Add(myString);
// No more digits
break;
}
}
When you run above code, you would get Alphabets & Digits separated as Lists.
🙂
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