C# Version of SQL Like

C# Version Of SQL LIKE

Regular expressions allow for everything that LIKE allows for, and much more, but have a completely different syntax. However, since the rules for LIKE are so simple(where % means zero-or-more characters and _ means one character), and both LIKE arguments and regular expressions are expressed in strings, we can create a regular expression that takes a LIKE argument (e.g. abc_ef% *usd) and turn it into the equivalent regular expression (e.g. \Aabc.ef.* \*usd\z):

@"\A" + new Regex(@"\.|\$|\^|\{|\[|\(|\||\)|\*|\+|\?|\\").Replace(toFind, ch => @"\" + ch).Replace('_', '.').Replace("%", ".*") + @"\z"

From that we can build a Like() method:

public static class MyStringExtensions
{
  public static bool Like(this string toSearch, string toFind)
  {
    return new Regex(@"\A" + new Regex(@"\.|\$|\^|\{|\[|\(|\||\)|\*|\+|\?|\\").Replace(toFind, ch => @"\" + ch).Replace('_', '.').Replace("%", ".*") + @"\z", RegexOptions.Singleline).IsMatch(toSearch);
  }
}

And hence:

bool willBeTrue = "abcdefg".Like("abcd_fg");
bool willAlsoBeTrue = "abcdefg".Like("ab%f%");
bool willBeFalse = "abcdefghi".Like("abcd_fg");

Like operator in SQL alternative in C#

Here is how the TSQL LIKE keyword works.

using System;

namespace SqlLike
{
    class Program
    {
        static void Main(string[] args)
        {
            var findMe = "ABCHelloXYZ";

            // LIKE '......%'
            if (findMe.StartsWith("ABC"))
            {
                Console.WriteLine("Yay");
            }

            // LIKE '%......'
            if (findMe.EndsWith("XYZ"))
            {
                Console.WriteLine("Woohoo");
            }

            // LIKE '%......%'
            if (findMe.Contains("Hello"))
            {
                Console.WriteLine("JackPot!!");
            }

            Console.ReadLine();
        }
    }
}

Use SQL LIKE operator in C# LINQ

There are lots of possibilities for Like in Linq:

For LIKE '%abc%';

list.Where(x => x.myTextColumn.Contains('abc'));

For LIKE 'abc%';

list.Where(x => x.myTextColumn.StartWith('abc'));

For LIKE '%abc';

list.Where(x => x.myTextColumn.EndsWith('abc'));

Updates : If you need to add Date comparison as well means you can do like the following:

DateTime date2Compare = new DateTime(2017, 1, 20);
list.Where(x => myDateColumn >= date2Compare && x.myTextColumn.Contains('abc'));

SQL LIKE Equivalent in C#

You could achieve your goal by using regular expressions. See Regex.Match Method.
You can transform your selected string from the dropdown list into a regular expression then use the Match method in your LINQ query.

Regex r = new Regex(String.Format ("Customer {0} has {1} orders", "([^\s]+)",  "([^\s]+)"));

This code:

o.CustomField.Contains(searchString)

can then be changed to:

r.Match(o.CustomField).Success

The equivalent of SQL's LIKE and _ wildcard in C#

I wrote this directly in the comment box (so this function may not compile) but you should use regular expressions. Something similar to this should work:

string GetWarehousByGrade222(string grade, string paste)
{
  if (grade == "00" || grade == "01" || grade == "02" || grade == "03" || grade == "04") {
    if (Regex.IsMatch(paste, "D..G..DG")) return "1GD";
    if (Regex.IsMatch(paste, "D..G..DP")) return "1GD";
    if (Regex.IsMatch(paste, "D..G..D.")) return "1GO";
    // etc...
  }
  return null;
}

C# Equivalent of SQL Server DataTypes

This is for SQL Server 2005. There are updated versions of the table for SQL Server 2008, SQL Server 2008 R2, SQL Server 2012 and SQL Server 2014.

SQL Server Data Types and Their .NET Framework Equivalents

The following table lists Microsoft SQL Server data types, their equivalents in the common language runtime (CLR) for SQL Server in the System.Data.SqlTypes namespace, and their native CLR equivalents in the Microsoft .NET Framework.

SELECT * FROM Contacts WHERE Name like @person + '%'

if(!String.IsNullOrEmpty(richTextBox_MWE.Text) && richTextBox_MWE.Text.Trim().Contains(textBox1.Text.Trim()))
{
  label5.BackColor = Color.Green;
}