blocks|key|4883215|text|According+to+Aaron+Bertand|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|4883216|4883217|您需要验证SQL+Server服务是否正在运行。您可以通过转到Start+>+Control+Panel+>+Administrative+Tools+>+Services并检查服务SQL+Server+(SQLEXPRESS)是否正在运行来完成此操作。|ordered-list-item|style|CODE|4883218|当您在服务小程序中时，还要确保服务SQL+Browser已启动。否则，start+it.|4883219|You需要确保允许SQL+Server使用TCP/IP或命名管道。您可以通过在Start+>+Programs+>+Microsoft+SQL+Server+2012+>+Configuration+Tools+(或SQL+Server+Configuration+Manager)和make+sure+that+TCP/IP+and+Named+Pipes+are+enabled中打开SQL+Server配置管理器来打开这些配置。如果在“开始”菜单中找不到SQL+Server配置管理器，则可以手动启动MMC管理单元。根据您的版本检查管理单元路径的SQL+Server+Configuration+Manager。|4883220|4883221|📷|atomic|4883222|​|4883223|4883224|验证您的SQL+Server连接身份验证模式是否与您的连接字符串匹配：|4883225|4883226|-+If+you're+connecting+using+a+username+and+password,+you+need+to+configure+SQL+Server+to+accept+"SQL+Server+Authentication+Mode":|code-block|syntax|javascript|4883227|+--运行此命令后必须重新启动SQL+SERVER！使用master+GO声明@SqlServerAndWindowsAuthenticationMode+INT+=+2；EXEC+xp_instance_regwrite+N‘’HKEY_LOCAL_MACHINE‘，N'Software\Microsoft\MSSQLServer\MSSQLServer'，N’‘LoginMode’，REG_DWORD，@SqlServerAndWindowsAuthenticationMode；GO|4883228|-如果你正在使用“集成Security=true”(Windows模式)进行连接，并且只有在web应用程序中调试时才会出现这个错误，那么你需要add+the+ApplicationPoolIdentity+as+a+SQL+Server+login|4883229|4883230|4883231|否则，请运行Start+->+Run+->+Services.msc如果是，它是否正在运行？|4883232|4883233|如果它没有运行，那么|4883234|听起来好像你没有把所有的东西都安装好。启动安装文件并选择"New+installation+or+add+features+to+an+existing+installation“选项。从那里，您应该能够确保安装了数据库引擎服务。|4883235|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/10624287/cant-connect-to-sql-server-2005-localhost/10625298#10625298|1|https://technet.microsoft.com/en-us/library/ms181087(v=sql.105).aspx|2|https://www.tenforums.com/tutorials/4499-start-stop-disable-services-windows-10-a.html|3|https://www.blackbaud.com/files/support/infinityinstaller/content/installermaster/tkenablenamedpipesandtcpipconnections.htm|4|https://docs.microsoft.com/en-us/sql/relational-databases/sql-server-configuration-manager|5|IMAGE|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/fe9324adf8dd0403c4783d9c9a2ed136.png|imageAlt|6|https://blogs.msdn.microsoft.com/ericparvin/2015/04/14/how-to-add-the-applicationpoolidentity-to-a-sql-server-login/^0|0|Q|0|0|0|V|1J|2V|A|0|H|B|1|Z|8|2|0|13|1U|30|W|3Y|1D|3|7O|W|4|0|0|0|1|5|0|0|0|0|0|0|0|1Z|1H|6|0|0|0|6|S|0|0|0|0^^$0|@$1|2|3|4|5|6|7|23|8|@]|9|@$A|24|B|25|1|26]]|C|$]]|$1|D|3|-4|5|6|7|27|8|@]|9|@]|C|$]]|$1|E|3|F|5|G|7|28|8|@$A|29|B|2A|H|I]|$A|2B|B|2C|H|I]]|9|@]|C|$]]|$1|J|3|K|5|G|7|2D|8|@]|9|@$A|2E|B|2F|1|2G]|$A|2H|B|2I|1|2J]]|C|$]]|$1|L|3|M|5|G|7|2K|8|@$A|2L|B|2M|H|I]|$A|2N|B|2O|H|I]]|9|@$A|2P|B|2Q|1|2R]|$A|2S|B|2T|1|2U]]|C|$]]|$1|N|3|-4|5|6|7|2V|8|@]|9|@]|C|$]]|$1|O|3|P|5|Q|7|2W|8|@]|9|@$A|2X|B|2Y|1|2Z]]|C|$]]|$1|R|3|S|5|6|7|30|8|@]|9|@]|C|$]]|$1|T|3|-4|5|6|7|31|8|@]|9|@]|C|$]]|$1|U|3|V|5|G|7|32|8|@]|9|@]|C|$]]|$1|W|3|-4|5|6|7|33|8|@]|9|@]|C|$]]|$1|X|3|Y|5|Z|7|34|8|@]|9|@]|C|$10|11]]|$1|12|3|13|5|6|7|35|8|@]|9|@]|C|$]]|$1|14|3|15|5|6|7|36|8|@]|9|@$A|37|B|38|1|39]]|C|$]]|$1|16|3|S|5|6|7|3A|8|@]|9|@]|C|$]]|$1|17|3|-4|5|6|7|3B|8|@]|9|@]|C|$]]|$1|18|3|19|5|G|7|3C|8|@$A|3D|B|3E|H|I]]|9|@]|C|$]]|$1|1A|3|-4|5|6|7|3F|8|@]|9|@]|C|$]]|$1|1B|3|1C|5|6|7|3G|8|@]|9|@]|C|$]]|$1|1D|3|1E|5|6|7|3H|8|@]|9|@]|C|$]]|$1|1F|3|-4|5|6|7|3I|8|@]|9|@]|C|$]]]|1G|$1H|$5|1I|1J|1K|C|$1L|1M]]|1N|$5|1I|1J|1K|C|$1L|1O]]|1P|$5|1I|1J|1K|C|$1L|1Q]]|1R|$5|1I|1J|1K|C|$1L|1S]]|1T|$5|1I|1J|1K|C|$1L|1U]]|1V|$5|1W|1J|1X|C|$1Y|1Z|20|-4]]|21|$5|1I|1J|1K|C|$1L|22]]]]

<a href="https://stackoverflow.com/questions/10624287/cant-connect-to-sql-server-2005-localhost/10625298#10625298">According to Aaron Bertand</a>:

<ol>
<li>You need to verify that the SQL Server service is running. You can do this by going to <code>Start &gt; Control Panel &gt; Administrative Tools &gt; Services</code>, and checking that the service SQL Server (<code>SQLEXPRESS</code>) is running. If not, start it.</li>
<li>While you're in the services applet, also make sure that the service <a href="https://technet.microsoft.com/en-us/library/ms181087(v=sql.105).aspx" rel="noreferrer">SQL Browser</a> is started. If not, <a href="https://www.tenforums.com/tutorials/4499-start-stop-disable-services-windows-10-a.html" rel="noreferrer">start it</a>.</li>
<li>You need to make sure that SQL Server is allowed to use TCP/IP or named pipes. You can turn these on by opening the SQL Server Configuration Manager in <code>Start &gt; Programs &gt; Microsoft SQL Server 2012 &gt; Configuration Tools</code> (or <code>SQL Server Configuration Manager</code>), and <a href="https://www.blackbaud.com/files/support/infinityinstaller/content/installermaster/tkenablenamedpipesandtcpipconnections.htm" rel="noreferrer">make sure that TCP/IP and Named Pipes are enabled</a>. If you don't find the SQL Server Configuration Manager in the Start Menu you can launch the MMC snap-in manually. Check <a href="https://docs.microsoft.com/en-us/sql/relational-databases/sql-server-configuration-manager" rel="noreferrer">SQL Server Configuration Manager</a> for the path to the snap-in according to your version.

<a href="https://i.stack.imgur.com/dPM5j.png" rel="noreferrer"><img src="https://i.stack.imgur.com/dPM5j.png" alt="SQL Server Configuration Manager"></a></li>
<li>Verify your SQL Server connection authentication mode matches your connection string:

<ul>
<li>If you're connecting using a username and password, you need to configure SQL Server to accept "SQL Server Authentication Mode":

<pre><code>-- YOU MUST RESTART YOUR SQL SERVER AFTER RUNNING THIS!
USE [master]
GO
DECLARE @SqlServerAndWindowsAuthenticationMode INT = 2;
EXEC xp_instance_regwrite
 N'HKEY_LOCAL_MACHINE',
 N'Software\Microsoft\MSSQLServer\MSSQLServer',
 N'LoginMode',
 REG_DWORD,
 @SqlServerAndWindowsAuthenticationMode;
GO
</code></pre></li>
<li>If you're connecting using "Integrated Security=true" (Windows Mode), and this error only comes up when debugging in web applications, then you need to <a href="https://blogs.msdn.microsoft.com/ericparvin/2015/04/14/how-to-add-the-applicationpoolidentity-to-a-sql-server-login/" rel="noreferrer">add the ApplicationPoolIdentity as a SQL Server login</a>:</li>
</ul></li>
<li>otherwise, run <code>Start -&gt; Run -&gt; Services.msc</code> If so, is it running?</li>
</ol>

If it's not running then

It sounds like you didn't get everything installed. Launch the install file and chose the option "New installation or add features to an existing installation". From there you should be able to make sure the database engine service gets installed.

blocks|key|2760551|text|我也遇到过类似的问题--也许我的解决方案会有所帮助。我刚刚安装了MSSQL+ex2012(默认安装)，并尝试连接VS2012+EX。不是，是joy。然后我查看了这些服务，确认SQL+Server+(SQLEXPRESS)确实在运行。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2760552|但是，我看到另一个有趣的服务，称为SQL+Server浏览器，它被禁用了。我启用它，启动它，然后能够在VS2012+EX中检索新连接中的服务器名称并进行连接。|2760553|奇怪的是，他们会禁用VS连接所需的服务。|2760554|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

I had a similar problem - maybe my solution will help. I just installed MSSQL EX 2012 (default install) and tried to connect with VS2012 EX. No joy. I then looked at the services, confirmed that SQL Server (SQLEXPRESS) was, indeed running.

However, I saw another interesting service called SQL Server Browser that was disabled. I enabled it, fired it and was then able to retrieve the server name in a new connection in VS2012 EX and connect.

Odd that they would disable a service required for VS to connect.

blocks|key|3242128|text|这很奇怪，我也有类似的问题。我下载了带有工具的SQL+2012+Express包，但没有安装数据库引擎。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3242129|我从MS站点上卸载了另一个，这个安装了数据库引擎。重新启动后，服务被列出并准备就绪。|3242130|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

This is odd I have a similar problem. I downloaded the package for SQL 2012 Express with Tools but the Database Engine was not install.

I donloaded the other one from the MS site and this one installed the database engine. After a reboot the services were listed and ready to go.

blocks|key|3242182|text|我的情况|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3242183|SQL+Server+Management+Studio中的|3242184|空实例名称>选择数据库引擎>鼠标右键>属性(服务器属性)>链接查看连接属性>产品>实例名称为空|unordered-list-item|3242185|Data+Source=.\SQLEXPRESS+=>+not+work+=>+use+localhost+in+web.config+(请参见下文)|3242186|3242187|Solution：在web.config中|offset|length|style|BOLD|3242188|​|3242189|xxxxxx+=不带.mdf的数据库的名称yyyyyy+=+VS2012数据库资源管理器中的数据库的名称|3242190|您可以强制使用TCP而不是共享内存，方法是在连接字符串中的服务器名称前加上tcp：，或者使用localhost。|3242191|http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnection.connectionstring%2528v=vs.110%2529.aspx|3242192|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnection.connectionstring%2528v=vs.110%2529.aspx^0|0|0|0|0|0|0|8|0|0|0|0|0|33|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|16|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|17|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|18|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|19|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|1A|8|@$L|1B|M|1C|N|O]]|9|@]|A|$]]|$1|P|3|Q|5|6|7|1D|8|@]|9|@]|A|$]]|$1|R|3|S|5|6|7|1E|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|1F|8|@]|9|@]|A|$]]|$1|V|3|W|5|6|7|1G|8|@]|9|@$L|1H|M|1I|1|1J]]|A|$]]|$1|X|3|-4|5|6|7|1K|8|@]|9|@]|A|$]]]|Y|$Z|$5|10|11|12|A|$13|14]]]]

My situation 

<ul>
<li>empty Instance Name in SQL Server Management Studio > select your database engine > Right Mouse Button > Properties (Server Properties) > Link View connection properties > Product > Instance Name is empty</li>
<li>Data Source=.\SQLEXPRESS did not work => use localhost in web.config (see below)</li>
</ul>

Solution: in web.config



xxxxxx = name of my database without .mdf
yyyyyy = name of my database in VS2012 database explorer

You can force the use of TCP instead of shared memory, either by prefixing tcp: to the server name in the connection string, or by using localhost.

<a href="http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnection.connectionstring%28v=vs.110%29.aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnection.connectionstring%28v=vs.110%29.aspx</a>

blocks|key|2760677|text|我也遇到了同样的问题，我发现这是在我为我的SQL+2012安装了更新之后发生的。对我来说，修复它的方法是进入程序和功能，并对其进行修复。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2760678|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I had the same issue and I found that this happened after I installed an update for my SQL 2012. What fixed it for me was going into programs and features and running a repair on it.

blocks|key|4883365|text|尝试从windows身份验证更改为混合模式|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4883366|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Try changing from windows authentication to mixed mode

blocks|key|3242303|text|转到开始->程序->+Microsoft+SQL+ServerYYYY+->+Configuration+Tools+->+SQL+Server+YYYY+Configuration+Manager或运行"SQLServerManager12.msc“。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3242304|确保在客户端协议下启用了TCP/IP。|3242305|然后进入"SQL+Server网络配置“并双击TCP/IP。单击"IP地址“选项卡并滚动到底部。在"IP+All“下删除TCP+Dynamic+Ports+(如果存在)，并将TCP+Port+(TCP端口)设置为1433。单击“确定”，然后返回到"SQL+Server服务“并重新启动SQL+Server实例。现在你可以通过localhost连接了，至少我可以。|3242306|​|3242307|📷|atomic|offset|length|3242308|3242309|请注意，当从其他应用程序连接时，当然也会发生此错误。普通C#+web应用程序Web.config连接字符串的示例：|style|CODE|3242310|<connectionStrings>
++++<add+name="DefaultConnection"+connectionString="server=localhost;database=myDb;uid=myUser;password=myPass;"+/>
</connectionStrings>|code-block|syntax|javascript|3242311|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/fc5e989a30f4f16b0f1f283e070601ce.png|imageAlt^0|0|0|0|0|0|1|0|0|0|12|A|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|16|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|17|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|18|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|19|8|@]|9|@$K|1A|L|1B|1|1C]]|A|$]]|$1|M|3|G|5|6|7|1D|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|1E|8|@$K|1F|L|1G|P|Q]]|9|@]|A|$]]|$1|R|3|S|5|T|7|1H|8|@]|9|@]|A|$U|V]]|$1|W|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13|14|-4]]]]

Goto Start -> Programs -> Microsoft SQL ServerYYYY -> Configuration Tools -> SQL Server YYYY Configuration Manager or run "SQLServerManager12.msc". 

Make sure that TCP/IP is enabled under Client Protocols.

Then go into "SQL Server Network Configuration" and double click TCP/IP. Click the "IP Addresses" tab and scroll to the bottom. Under "IP All" remove TCP Dynamic Ports if it is present and set TCP Port to 1433. Click OK and then go back to "SQL Server Services" and restart SQL Server instance. Now you can connect via localhost, at least I could.

<a href="https://i.stack.imgur.com/ogkmm.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ogkmm.png" alt="enter image description here"></a>

Note that this error can of course occur when connecting from other applications as well. Example for a normal C# web application <code>Web.config</code> connection string:

<pre><code>&lt;connectionStrings&gt;
 &lt;add name="DefaultConnection" connectionString="server=localhost;database=myDb;uid=myUser;password=myPass;" /&gt;
&lt;/connectionStrings&gt;
</code></pre>

blocks|key|3242376|text|首先检查SQL+Server服务是否正在运行或已停止，如果已停止，则启动它，执行so..just操作，请执行以下步骤。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3242377|1.启动->运行->Services.msc|3242378|​|3242379|📷|atomic|offset|length|3242380|3242381|3242382|转到服务面板中的标准选项卡，然后搜索SQl+SQl|ordered-list-item|3242383|3242384|3242385|+"SQL2014“是我给的，它可能是你的另一个名字|blockquote|3242386|3242387|3242388|3242389|3242390|3242391|一旦你启动SQL服务，你就可以连接本地数据库了。|3242392|希望它能帮助到一些人。|3242393|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/eb6e31d512c1e75ea5e585edb3d1748c.png|imageAlt|1|https://ask.qcloudimg.com/http-save/yehe-900000/8fff6e4b89601318038c4f8dd090d7e2.png^0|0|0|0|0|1|0|0|0|0|0|0|0|0|0|0|0|0|1|1|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1F|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1G|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|1H|8|@]|9|@$I|1I|J|1J|1|1K]]|A|$]]|$1|K|3|E|5|6|7|1L|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|1M|8|@]|9|@]|A|$]]|$1|M|3|N|5|O|7|1N|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|1O|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]|$1|R|3|S|5|T|7|1Q|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1R|8|@]|9|@]|A|$]]|$1|V|3|-4|5|6|7|1S|8|@]|9|@]|A|$]]|$1|W|3|E|5|6|7|1T|8|@]|9|@]|A|$]]|$1|X|3|G|5|H|7|1U|8|@]|9|@$I|1V|J|1W|1|1X]]|A|$]]|$1|Y|3|E|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|Z|3|10|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|20|8|@]|9|@]|A|$]]|$1|13|3|-4|5|6|7|21|8|@]|9|@]|A|$]]]|14|$15|$5|16|17|18|A|$19|1A|1B|-4]]|1C|$5|16|17|18|A|$19|1D|1B|-4]]]]

First check SQL Server Service is Running or stopped, if it is stopped just start it, to do so..just follow the below steps.

1.Start -> Run ->Services.msc

<a href="https://i.stack.imgur.com/AM9yT.png" rel="noreferrer"><img src="https://i.stack.imgur.com/AM9yT.png" alt="enter image description here"></a>

<ol start="2">
<li>Go to Standard tab in services panel then search for SQl Server(SQL2014)</li>
</ol>

<blockquote>
 "SQL2014" is given By me, it may be Another Name in your case
</blockquote>

<a href="https://i.stack.imgur.com/OkPeJ.png" rel="noreferrer"><img src="https://i.stack.imgur.com/OkPeJ.png" alt="enter image description here"></a>

that's it once you start the SQL Service, you are able to connect local database.

hope it will help someone.

blocks|key|4883533|text|在SQL+SERVER+EXPRESS+2012中，应使用"(localdb)\MSSQLLocalDB“作为数据源名称。例如，可以使用如下所示的连接字符串|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4883534|Data+Source=(localdb)\MSSQLLocalDB;Initial+Catalog=master;Integrated+Security=True;|code-block|syntax|javascript|4883535|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

in SQL SERVER EXPRESS 2012 you should use "(localdb)\MSSQLLocalDB" as Data Source name
for example you can use connection string like this

<pre><code>Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=master;Integrated Security=True;
</code></pre>

blocks|key|3242581|text|首先尝试Ravindra+Bagale提供的最流行的解决方案。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3242582|如果从localhost到数据库的连接仍然失败，并出现类似以下的错误：|3242583|3242584|无法连接到SQL+Server+DB。错误:到主机IP地址、端口1433的TCP/IP连接失败。错误：“连接被拒绝:连接。请验证连接属性。确保SQL+Server实例正在主机上运行并在该端口接受TCP/IP连接。确保到该端口的TCP连接未被防火墙阻止。”|blockquote|3242585|3242586|3242587|打开服务器实例的SQL+server+Configuration+Manager.|3242588|Expand+SQL+Server+Network+Configuration在“|unordered-list-item|3242589|
|3242590|”部分中，将"Enabled“设置为”Yes“。在"IP+Addresses”部分下，设置"IP+|3242591|
“下的|3242592|端口(这是1433+by+question.|3242593|3242594|Double-click+"TCP/IP".|3242595|3242596|Under+"IP+Addresses”部分，找到IP地址为127.0.0.1+(对于IPv4)和::1+(对于IPv6)的子节，并将"Enabled“和"Active”都设置为"Yes"，并将TCP端口设置为1433。|3242597|3242598|📷|atomic|3242599|​|3242600|3242601|转到Start+>+Control+Panel+>+Administrative+Tools+>+Services，然后重新启动SQL+Server服务的SQL+Server|ordered-list-item|style|CODE|3242602|3242603|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/12774856/1429387|1|IMAGE|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/ca2843a5b2a8e3c989d41f2e382c5036.png|imageAlt^0|4|F|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|1|1|0|0|0|2|1J|0|0^^$0|@$1|2|3|4|5|6|7|1V|8|@]|9|@$A|1W|B|1X|1|1Y]]|C|$]]|$1|D|3|E|5|6|7|1Z|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|20|8|@]|9|@]|C|$]]|$1|G|3|H|5|I|7|21|8|@]|9|@]|C|$]]|$1|J|3|-4|5|6|7|22|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|23|8|@]|9|@]|C|$]]|$1|L|3|M|5|6|7|24|8|@]|9|@]|C|$]]|$1|N|3|O|5|P|7|25|8|@]|9|@]|C|$]]|$1|Q|3|R|5|6|7|26|8|@]|9|@]|C|$]]|$1|S|3|T|5|P|7|27|8|@]|9|@]|C|$]]|$1|U|3|V|5|6|7|28|8|@]|9|@]|C|$]]|$1|W|3|X|5|P|7|29|8|@]|9|@]|C|$]]|$1|Y|3|R|5|6|7|2A|8|@]|9|@]|C|$]]|$1|Z|3|10|5|P|7|2B|8|@]|9|@]|C|$]]|$1|11|3|R|5|6|7|2C|8|@]|9|@]|C|$]]|$1|12|3|13|5|P|7|2D|8|@]|9|@]|C|$]]|$1|14|3|-4|5|6|7|2E|8|@]|9|@]|C|$]]|$1|15|3|16|5|17|7|2F|8|@]|9|@$A|2G|B|2H|1|2I]]|C|$]]|$1|18|3|19|5|6|7|2J|8|@]|9|@]|C|$]]|$1|1A|3|-4|5|6|7|2K|8|@]|9|@]|C|$]]|$1|1B|3|1C|5|1D|7|2L|8|@$A|2M|B|2N|1E|1F]]|9|@]|C|$]]|$1|1G|3|-4|5|6|7|2O|8|@]|9|@]|C|$]]|$1|1H|3|-4|5|6|7|2P|8|@]|9|@]|C|$]]]|1I|$1J|$5|1K|1L|1M|C|$1N|1O]]|1P|$5|1Q|1L|1R|C|$1S|1T|1U|-4]]]]

First try the most popular solution provided by <a href="https://stackoverflow.com/a/12774856/1429387">Ravindra Bagale</a>.

If your connection from localhost to the database still fails with error similar to the following:

<blockquote>
 Can't connect to SQL Server DB. Error: The TCP/IP connection to the host [IP address], port 1433 has failed. Error: "Connection refused: connect. Verify the connection properties. Make sure that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port. Make sure that TCP connections to the port are not blocked by a firewall."
</blockquote>

<ol>
<li>Open the SQL Server Configuration Manager.</li>
<li>Expand SQL Server Network Configuration for the server instance in question.</li>
<li>Double-click "TCP/IP".</li>
<li>Under the "Protocol" section, set "Enabled" to "Yes".</li>
<li>Under the "IP Addresses" section, set the TCP port under "IP All" (which is 1433 by default).</li>
<li>Under the "IP Addresses" section, find subsections with IP address 127.0.0.1 (for IPv4) and ::1 (for IPv6) and set both "Enabled" and "Active" to "Yes", and TCP port to 1433.

<a href="https://i.stack.imgur.com/NU0r8.png" rel="noreferrer"><img src="https://i.stack.imgur.com/NU0r8.png" alt="TCP/IP Properties"></a></li>
<li>Go to <code>Start &gt; Control Panel &gt; Administrative Tools &gt; Services</code>, and restart the SQL Server service (<code>SQLEXPRESS</code>).</li>
</ol>

blocks|key|4971397|text|我的所有服务都在按预期运行，但我仍然无法连接。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4971398|我必须为我的SQL+Server+Express协议更新SQL+Server配置管理器中的TCP/IP属性部分，并将IPALL端口设置为1433，以便按预期连接到服务器。|4971399|​|4971400|📷|atomic|offset|length|4971401|4971402|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/b8fbe0a96b7e3817031ce6056cfe3a2c.png|imageAlt^0|0|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@$I|Y|J|Z|1|10]]|A|$]]|$1|K|3|E|5|6|7|11|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|S|T|-4]]]]

All my services were running as expected, and I still couldn't connect.

I had to update the TCP/IP properties section in the SQL Server Configuration Manager for my SQL Server Express protocols, and set the IPALL port to 1433 in order to connect to the server as expected.

<a href="https://i.stack.imgur.com/gsTOo.png" rel="noreferrer"><img src="https://i.stack.imgur.com/gsTOo.png" alt="enter image description here"></a>

blocks|key|4883860|text|对我来说，问题是我没有指定.\。我只是指定了实例的名称：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4883861|SQL2016|4883862|worked：.\SQL2016|unordered-list-item|4883863|
：|4883864|不起作用|4883865|4883866|entityMap^0|D|2|0|0|7|0|7|9|0|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|K|3|L|5|6|7|10|8|@]|D|@]|E|$]]|$1|M|3|N|5|J|7|11|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|12|8|@]|D|@]|E|$]]|$1|P|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|Q|$]]

The problem for me was that I was not specifying <code>.\</code>. I was only specifying the name of the instance:

<ul>
<li>did not work: <code>SQL2016</code></li>
<li>worked: <code>.\SQL2016</code></li>
</ul>

blocks|key|3242709|text|尝试将拥有该服务的用户更改为本地系统或使用您的管理员帐户。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3242710|在services下，我更改了Service+SQL+Server+(MSSQLSERVER)+Log+On+from+NT+Service\Sql...到本地系统。右键单击该服务并转到Log+On选项卡，然后选择单选按钮Local+System+Account。您还可以强制其他用户也运行它，如果这样更合适的话。|3242711|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Try changing the User that owns the service to Local System or use your admin account.

Under services, I changed the Service SQL Server (MSSQLSERVER) Log On from NT Service\Sql... To Local System. Right click the service and go to the Log On Tab and select the radio button Local System Account. You could also force another User to run it too if that fits better.

blocks|key|4971462|text|在完成@Ravindra+Bagale提到的步骤之后，尝试以下步骤。Server+name:+localhost\{Instance+name+you+were+gave}|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|4971463|​|4971464|📷|atomic|4971465|4971466|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/dc021c6d3601e729d2da11186511a95c.png|imageAlt^0|4|F|Y|1G|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|D]]|E|@]|F|$]]|$1|G|3|H|5|6|7|10|8|@]|E|@]|F|$]]|$1|I|3|J|5|K|7|11|8|@]|E|@$9|12|A|13|1|14]]|F|$]]|$1|L|3|H|5|6|7|15|8|@]|E|@]|F|$]]|$1|M|3|-4|5|6|7|16|8|@]|E|@]|F|$]]]|N|$O|$5|P|Q|R|F|$S|T|U|-4]]]]

After doing the steps which were mentioned by @Ravindra Bagale, 
Try this step. 
<code>Server name: localhost\{Instance name you were gave}</code>

<a href="https://i.stack.imgur.com/9fhn2.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9fhn2.png" alt="enter image description here"></a>

I just downloaded the latest version of SQL Express 2012 but I cannot connect to localhost. I tried localhost\SQLExpress and Windows authentication but it gives me an error message saying cannot connect. Am I missing something here? I've used SQL Server 2008 before and I've never had issues connecting to localhost. It seems that it can't even find it. Also in the Services I only see a SQL Server VSS Writer. Is this the way it should be? Or am I missing something? Thanks

Can't connect to localhost on SQL Server Express 2012 / 2016

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我刚刚下载了SQL Express 2012的最新版本，但无法连接到localhost。我尝试了localhost\SQLExpress和Windows身份验证，但它给我一条错误消息，告诉我无法连接。我是不是漏掉了什么？我以前使用过SQL Server2008，连接到localhost时从来没有遇到过问题。看起来它甚至...

问无法连接到SQL Server Express 2012 / 2016上的本地主机
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