C# SqlConnection could not be found

Question

I am trying to connect to the SQL database in my network using the code below. I've searched on Stackoverflow and web for this error and found so many other people experiencing this issue, applied and tested many none fixed my issue. Currently the code I have is below:

using System;
using System.Data.SqlClient;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            using ( SqlConnection conn = new SqlConnection)
            {
                conn.ConnectionString = "Server=***;Database=***;Trusted_Connection=True;";
            }
        }
    }
}

In the place of *** I have server and database names. Also, where do I enter the specific table?

What exact error are you facing? You'd put the table name in the query, which you specify when you create a command. Note that you need () after new SqlConnection. — Jon Skeet
– Jon Skeet, Commented Dec 3, 2018 at 14:58
a table would be part of a specific query, and you aren't showing any queries; the code you've shown shouldn't compile - it would need to be using (SqlConnection conn new SqlConnection()) (note extra parentheses) - but: the error suggests the problem is resolving the type itself; is this a missing reference? Are you referencing System.Data? or if this is .NET Core: System.Data.SqlClient (package reference)? — Marc Gravell
– Marc Gravell, Commented Dec 3, 2018 at 14:59
oh okay. In visual studio where there is SqlConnection text, there is red line under it when I go over it says "The type or namespace name 'SqlConnection' could not be found( are you missing a using directive oran assembly reference?) " and gives me show potential fixes but those create a new file. — Peace
– Peace, Commented Dec 3, 2018 at 15:01
I think it might be worth stopping this line of dev right now and taking a look at entity framework.. In an hour you'll be writing command.CommandText="SELECT * FROM table WHERE id = " + Textbox1.Text; and the fight to save another developer from spending the next 5 years writing insecure, low quality database access code will be lost :/ — Caius Jard
– Caius Jard, Commented Dec 3, 2018 at 15:01

David Browne - Microsoft · Accepted Answer · 2018-12-03 15:08:12Z

15

All I did was create a new console app and enter this code to connect to DB.

So I can infer that you're using .NET Core, and so you need to add the NuGet package: System.Data.SqlClient

Your .csproj file should look like:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.1</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="System.Data.SqlClient" Version="4.5.1" />
  </ItemGroup>

</Project>

answered Dec 3, 2018 at 15:08

David Browne - Microsoft

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4 Comments

Peace Over a year ago

Okay, I went to "ConsoleApp2\ConsoleApp2" folder and replaced the code in the .csproj with the code above, no more red lines under SqlConnection string.

David Browne - Microsoft Over a year ago

In Visual Studio you can manage your NuGet dependencies by right-clicking on the "Dependencies" node under your project in the Solution Explorer, or by using the "Package Manager Console". Of course editing the .csproj file is supported too.

Ankita Over a year ago

I did the same as mentioned by @Peace! And the red lines under SqlConnection string went away. But, I cannot find the Form in the Design Mode anymore. On executing the .exe application the Windows Form comes up but no longer able to edit the Form in Design Mode. Any ideas how to fix it ?

David Browne - Microsoft Over a year ago

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