c#连接SQL数据库的使用方法

1提取单条记录

//using SystemData;

//using SystemDataSqlClient;

using (SqlConnection cn = new SqlConnection(%%1))

//ConfigurationManagerConnectionStrings["db2ConnectionString"]ConnectionString

//Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;

{

SqlCommand cmd = new SqlCommand("Select Count() From jobs",cn);

cnOpen();

%%2=cmdExecuteScalar(); //MessageInnerHtml

}

2单值比较

//using SystemData;

//using SystemDataSqlClient;

using (SqlConnection cn = new SqlConnection(%%1))

//ConfigurationManagerConnectionStrings["db2ConnectionString"]ConnectionString

//Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;

{

SqlCommand cmd = new SqlCommand("Select Count() From jobs",cn);

cnOpen();

%%2=cmdExecuteScalar(); //MessageInnerHtml

if(%%2==%%3)

{

%%4

}

}

3显示表格

//using SystemData;

//using SystemDataSqlClient;

DataSet ds=null;

using (SqlConnection cn = new SqlConnection(%%1))

//ConfigurationManagerConnectionStrings["db2ConnectionString"]ConnectionString

//Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;

{

cnOpen();

cmd=new SqlDataAdapter("Select From Author",cn);

ds=new DataSet();

cmdFill(ds,%%2); //"作者"

MyDataGridDataSource=dsTables(%%2)DefaultView; //"作者"

MyDataGridDataBind();

}

4 *** 作表格

//using SystemData;

//using SystemDataSqlClient;

using (SqlConnection cn = new SqlConnection(%%1))

//ConfigurationManagerConnectionStrings["db2ConnectionString"]ConnectionString

//Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;

{

cnOpen();

cmd=new SqlDataAdapter("Select From Author",cn);

ds=new DataSet();

cmdFill(ds,%%2); //"作者"

MyDataGridDataSource=dsTables(%%2)DefaultView; //"作者"

MyDataGridDataBind();

}

5数值范围查询

//using SystemData;

//using SystemDataSqlClient;

using (SqlConnection cn = new SqlConnection(%%1))

//ConfigurationManagerConnectionStrings["db2ConnectionString"]ConnectionString

//Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;

{

}

6关闭时断开连接

//using SystemData;

//using SystemDataSqlClient;

using (SqlConnection cn = new SqlConnection(%%1))

//ConfigurationManagerConnectionStrings["db2ConnectionString"]ConnectionString

//Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;

{

}

7执行命令

//using SystemData;

//using SystemDataSqlClient;

using (SqlConnection cn = new SqlConnection(%%1))

//ConfigurationManagerConnectionStrings["db2ConnectionString"]ConnectionString

//Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;

{

SqlCommand cmd = new SqlCommand("insert userRegister_t values('"

+ TextBox1Text + "','" + TextBox2Text + "')",cn);

cnOpen();

cmdExecuteNonQuery();

}

7Oracle8/8i/9i数据库（thin模式）

//using SystemData;

Oracle Set Your custom connection strings values

ODBC

New version

Driver={Microsoft ODBC for Oracle};Server=myServerAddress;Uid=myUsername;Pwd=myPassword;

Old version

Driver={Microsoft ODBC Driver for Oracle};ConnectString=OracleServerworld;Uid=myUsername;Pwd=myPassword;

OLE DB, OleDbConnection (NET)

Standard security

This connection string uses a provider from Microsoft

Provider=msdaora;Data Source=MyOracleDB;User Id=myUsername;Password=myPassword;

Standard Security

This connection string uses a provider from Oracle

Provider=OraOLEDBOracle;Data Source=MyOracleDB;User Id=myUsername;Password=myPassword;

Trusted Connection

Provider=OraOLEDBOracle;Data Source=MyOracleDB;OSAuthent=1;

OracleConnection (NET)

Standard

Data Source=MyOracleDB;Integrated Security=yes;

This one works only with Oracle 8i release 3 or later

Specifying username and password

Data Source=MyOracleDB;User Id=myUsername;Password=myPassword;Integrated Security=no;

This one works only with Oracle 8i release 3 or later

Missing the SystemDataOracleClient namespace Download NET Managed Provider for Oracle >>

Great article! "Features of Oracle Data Provider for NET" by Rama Mohan G at C# Corner >>

Omiting tnsnamesora

This is another type of Oracle connection string that doesn't rely on you to have a DSN for the connection You create a connection string based on the format used in the tnsnamesora file without the need to actually have one of these files on the client pc

SERVER=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=MyHost)(PORT=MyPort))(CONNECT_DATA=(SERVICE_NAME=MyOracleSID)));uid=myUsername;pwd=myPassword;

Core Labs OraDirect (NET)

Standard

User ID=myUsername;Password=myPassword;Host=ora;Pooling=true;Min Pool Size=0;Max Pool Size=100;Connection Lifetime=0;

Read more at Core Lab >>

And at the product page >>

Data Shape

MS Data Shape

Provider=MSDataShape1;Persist Security Info=False;Data Provider=MSDAORA;Data Source=orac;User Id=myUsername;Password=myPassword;

16程序计时

DateTime runTime = ConvertToDateTime(SystemConfigurationConfigurationSettingsAppSettings["TimerRunAt"]);

//运行时间

TimeSpan runTime = new TimeSpan(runTimeTicks);

//现在时间

TimeSpan timeNow = new TimeSpan(DateTimeNowTicks);

//时间间隔

TimeSpan ts = runTimeSubtract(timeNow);

//如果运行时间与当前时间的差大于0，则任务执行时间为当日

if(tsTotalMilliseconds > 0)

{

return tsTotalMilliseconds;

}

//如果运行时间与当前时间的差小于0，则任务执行时间为次日

Else

{

//差值的绝对值应加1天

return tsDuration()Add(new TimeSpan(1,0,0,0,0))TotalMilliseconds;

}

17延时

//using SystemThreading;

ThreadSleep(Int32Parse(%%1));

18连接Excel文件

string connString = "Provider=MicrosoftJetOLEDB40;Data Source=" + excel文件名（绝对路径） +";Extended Properties=Excel 80;";

连接MYSQL数据库的方法及示例

方法一：

使用MYSQL推出的MySQL

Connector/Net

is

an

ADONET

driver

for

MySQL

该组件为MYSQL为ADONET访问MYSQL数据库设计的NET访问组件。

安装完成该组件后，引用命名空间MySqlDataMySqlClient;

使用命令行编译时：csc

/r:MySqlDatadll

testcs

方法二：

通过ODBC访问MYSQL数据库

访问前要先下载两个组件：odbcnet和MYSQL的ODBC驱动(MySQL

Connector/ODBC

(MyODBC)

driver)目前为351版

安装完成后，即可通过ODBC访问MYSQL数据库

方法三：

使用CoreLab推出的MYSQL访问组件，面向NET

安装完成后，引用命名空间：CoreLabMySql;

使用命令编译时：csc

/r:CoreLabMySqldll

testcs

以下为访问MYSQL数据库实例

编译指令：csc

/r:CoreLabMySqldll

/r:MySqlDatadll

testcs

using

System;

using

SystemNet;

using

SystemText;

using

CoreLabMySql;

using

SystemDataOdbc;

using

MySqlDataMySqlClient;

class

ConnectMySql

{

public

void

Connect_CoreLab()

{

string

c;

MySqlConnection

mycn

=

new

MySqlConnection(constr);

mycnOpen();

MySqlCommand

mycm

=

new

MySqlCommand("select

from

shop",mycn);

MySqlDataReader

msdr

=

mycmExecuteReader();

while(msdrRead())

{

if

(msdrHasRows)

{

ConsoleWriteLine(msdrGetString(0));

}

}

msdrClose();

mycnClose();

}

public

void

Connect_Odbc()

{

//string

MyC;

string

MyC

+

"SERVER=localhost;"

+

"DATABASE=test;"

+

"UID=root;"

+

"PASSWORD=qing;"

+

"OPTION=3";

OdbcConnection

MyConn

=

new

OdbcConnection(MyConString);

MyConnOpen();

OdbcCommand

mycm

=

new

OdbcCommand("select

from

hello",MyConn);

OdbcDataReader

msdr

=

mycmExecuteReader();

while(msdrRead())

{

if

(msdrHasRows)

{

ConsoleWriteLine(msdrGetString(0));

}

}

msdrClose();

MyConnClose();

}

public

void

Connect_Net()

{

string

myC;

MySqlConnection

mycn

=

new

MySqlConnection(myConnectionString);

mycnOpen();

MySqlCommand

mycm

=

new

MySqlCommand("select

from

hello",mycn);

MySqlDataReader

msdr

=

mycmExecuteReader();

while(msdrRead())

{

if

(msdrHasRows)

{

ConsoleWriteLine(msdrGetString(0));

}

}

msdrClose();

mycnClose();

}

public

static

void

Main()

{

ConnectMySql

ms

=

new

ConnectMySql();

msConnect_CoreLab();

msConnect_Odbc();

Connect_Net();

}

}

缺少dll net core 版本 有点问题 引用的dll 不会自动输出到项目目录下去，需要手动拷过去，或者在项目里指定复制到项目目录 ，你看看你的mysql是不是引用了第三方的库 并且在输出目录下没有生成这个dll ，好像在vs2017 153以后就没有这个问题了

缺少dll net core 版本 有点问题 引用的dll 不会自动输出到项目目录下去，需要手动拷过去，或者在项目里指定复制到项目目录 ，你看看你的mysql是不是引用了第三方的库 并且在输出目录下没有生成这个dll ，好像在vs2017 153以后就没有这个问题了

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