What is wrong with this code. Why can't I use SqlConnection?

Question

I am 100% newbie to SQl and wanted to make a ConsoleApp with the use of database. I read some about it and tried. When I needed to make SqlConnection, my VS 2019 Preview showed me this

Severity Code Description Project File Line Suppression State Error CS1069 The type name 'SqlConnection' could not be found in the namespace 'System.Data.SqlClient'. This type has been forwarded to assembly 'System.Data.SqlClient, Version=0.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' Consider adding a reference to that assembly. ConsoleApp1 C:\Users\User\Desktop\Bald Code\ConsoleApp1\ConsoleApp1\Program.cs 12 Active

i don't get why it doesn't work

Here's my code

using System;

using System.Data;

using System.Data.SqlClient;

namespace ConsoleApp1

{

    class Program
    {
        static void Main(string[] args)
        {
            string connectionString;
            SqlConnection cnn;
        }
    }
}

you need to add the System.Data.SqlClient assembly in your project reference. — peeyush singh, Feb 01 '19 at 02:47

score 47 · Answer 1 · answered Dec 14 '19 at 07:41

47

If you just updated EntityFrameworkCore from version 2.x to 3.x and you're running into this, change your using statement to Microsoft.Data.SqlClient instead of System.Data.SqlClient.

If you're using EntityFrameworkCore.SqlServer it already has that as a dependency, so you shouldn't need to install it explicitly.

This Microsoft blog explains the change.

answered Dec 14 '19 at 07:41

Chad Hedgcock

11,125
3
36
44

Not working... Microsoft doesn't have Data.SqlClient in it. – Ahmed Eissa Oct 14 '20 at 15:52
4

https://www.nuget.org/packages/Microsoft.Data.SqlClient/2.0.1 – Chad Hedgcock Oct 15 '20 at 15:04

score 29 · Answer 2 · answered Feb 23 '21 at 21:17

Most likely the System.Data.SqlClient.DLL in not in the Bin folder, and you have not set reference to the DLL in the project. You have missed the database choice when You install visual studio. And now You just manually add references named "System.Data.SqlClient".

1.right click you project name and choose nuget package options.

2.search "System.Data.SqlClient" and install it.

Hope this is fix Your Error

score 26 · Answer 3 · answered Feb 01 '19 at 02:50

26

Assuming that you're using .NET Core - just add NuGet package: System.Data.SqlClient

Your .csproj might look similar to:

<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 Feb 01 '19 at 02:50

jazb

5,498
6
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4

I had a similar problem despite adding the package from NuGet in VS2017. I had to close the project and re-open it for System.Data.SqlClient to be recognized. – Mmm Mar 27 '19 at 23:29

Ian · Answer 4 · 2021-10-04T17:22:10.483

The specific way to fix this from within VS Code is to

Open a terminal by going to Terminal -> New Terminal
Run dotnet add package System.Data.SqlClient
Run dotnet restore

That last command might not be necessary, but doing this made it work for me. It seems that console app templates don't come prepared for a reference to SqlClient.

Update

I think moving forward projects should use Microsoft.Data.SqlClient and not System.Data.SqlClient: https://devblogs.microsoft.com/dotnet/introducing-the-new-microsoftdatasqlclient/.

score 2 · Answer 5 · answered Jul 11 '19 at 08:47

2

As @Mmm mentioned in the comments if you are using .NET Core and have already installed the System.Data.SqlClient package, closing and reopening the project resolved the issue for me too.

answered Jul 11 '19 at 08:47

AMouat

685
15
27

Indiana Lora · Answer 6 · 2020-11-07T00:11:28.867

0

I had that error today and what's happening its that VS CODE its no recognizing System.Data.SqlClient;, that's why you can't call the variable...

How did I fix it??

I installed:

SQL server compact toolbox
Nuget Package version updater

Close visual studio/Open it again and your program should be rocking and popping!!

edited Nov 07 '20 at 00:11

answered Nov 06 '20 at 19:36

Indiana Lora

1
2

score 0 · Answer 7 · answered Nov 19 '20 at 20:21

[!["Manage Nuget Package for Solution"]

it fixed my issue. [1]: https://i.stack.imgur.com/hpk2e.png

I just installed nuget package from the "Manage Nuget Package for Solution". Previously I had used through command but that did not work so I used the UI to install this package.

score 0 · Answer 8 · answered Dec 31 '21 at 16:56

0

NuGet Package

Install-Package System.Data.SqlClient

solve my problem.

answered Dec 31 '21 at 16:56

Aminur Rahman

400
1
6
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score 0 · Answer 9 · answered Jan 20 '22 at 10:26

0

For me System.Data.SqlClient was already installed. What i had to do was, I went to the Nuget package manager and downgrade the version to 4.8.2 from 4.8.3 and it worked.

answered Jan 20 '22 at 10:26

Akang Toshi

193
5
17

1

4.8.2 did not work for me. At runtime I get an error expecting 4.6.1.2 – Kirsten May 20 '22 at 00:25

HarshSharma · Answer 10 · 2023-03-24T13:18:24.163

If none of the previous solutions has worked for you then try changing the version of System.Data.SqlClient in the project file to 0.0.0 or 4.1.0 because this is what the error is saying to use this version. After you change the version compile the code and once compiled then you can change the version of the library to the original one.

Note: The current version of the library I had was 4.8.5. Also, I tried all of the above solutions but none worked for me except for this one.

score -1 · Answer 11 · answered May 20 '21 at 15:43

-1

It's pretty simple

Go to solution explorer > right click & click manage NuGet packages > and install System.data.SqlClient 4.5.1. or later.

Click here to screenshot

answered May 20 '21 at 15:43

prineth fernando

3
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5

1

welcome to stack overflow. You answer is the same as many of the previous ones and does not add anything new or helpful to the post. When you have enough reputation, you could upvote an existing answer instead of duplicating it which you should avoid – Guy Levy May 20 '21 at 20:19

What is wrong with this code. Why can't I use SqlConnection?

11 Answers11

I installed:

Linked

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