时间:2021-07-01 10:21:17 帮助过:2人阅读
- <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">void</span> Main(<span style="color: #0000ff;">string</span><span style="color: #000000;">[] args)
- {
- </span><span style="color: #008000;">//</span><span style="color: #008000;">SqlConnection conn = new SqlConnection();</span><span style="color: #008000;">//</span><span style="color: #008000;">实例化
- </span><span style="color: #008000;">//</span><span style="color: #008000;">conn.ConnectionString = "server=.;database=mydb;uid=sa;pwd=123";</span><span style="color: #008000;">//</span><span style="color: #008000;">初始化-----可以用下面一条语句执行</span>
- SqlConnection conn = <span style="color: #0000ff;">new</span> SqlConnection(<span style="color: #800000;">"</span><span style="color: #800000;">server=.;database=mydb;uid=sa;pwd=123</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- Console.WriteLine(conn.State);
- conn.Open();</span><span style="color: #008000;">//</span><span style="color: #008000;">打开数据库连接</span>
- <span style="color: #000000;"> Console.WriteLine(conn.State);
- conn.Close();</span><span style="color: #008000;">//</span><span style="color: #008000;">关闭数据库连接</span>
- <span style="color: #000000;"> Console.WriteLine(conn.State);
- }</span>
连接数据库并插入数据
- <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">void</span> Main(<span style="color: #0000ff;">string</span><span style="color: #000000;">[] args)
- {
- SqlConnection conn </span>= <span style="color: #0000ff;">new</span> SqlConnection(<span style="color: #800000;">"</span><span style="color: #800000;">server=.;database=mydb;uid=sa;pwd=123</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- conn.Open();
- SqlCommand cmd </span>= <span style="color: #0000ff;">new</span><span style="color: #000000;"> SqlCommand();
- cmd.Connection </span>= conn;<span style="color: #008000;">//</span><span style="color: #008000;">初始化,通过conn数据对象连接数据库</span>
- cmd.CommandText = <span style="color: #800000;">"</span><span style="color: #800000;">insert into info values(‘p005‘,‘学生‘,‘0‘,‘n001‘,‘1990-02-1‘)</span><span style="color: #800000;">"</span>;<span style="color: #008000;">//</span><span style="color: #008000;">""内为SQL语句</span>
- <span style="color: #000000;"> cmd.ExecuteNonQuery();
- conn.Close();
- Console.WriteLine(</span><span style="color: #800000;">"</span><span style="color: #800000;">OK</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- }</span>
连接数据库并修改数据
- <span style="color: #0000ff;">public</span> <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">void</span> Main(<span style="color: #0000ff;">string</span><span style="color: #000000;">[] args)
- {
- SqlConnection conn </span>= <span style="color: #0000ff;">new</span> SqlConnection(<span style="color: #800000;">"</span><span style="color: #800000;">server=.;database=mydb;uid=sa;pwd=123</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- conn.Open();
- SqlCommand cmd </span>= <span style="color: #0000ff;">new</span><span style="color: #000000;"> SqlCommand();
- cmd.Connection </span>=<span style="color: #000000;"> conn;
- cmd.CommandText </span>= <span style="color: #800000;">"</span><span style="color: #800000;">update info set name=‘学员‘ where code=‘p005‘</span><span style="color: #800000;">"</span><span style="color: #000000;">;
- cmd.ExecuteNonQuery();
- conn.Close();
- }</span>
连接数据库并删除数据
- <span style="color: #0000ff;"> public</span> <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">void</span> Main(<span style="color: #0000ff;">string</span><span style="color: #000000;">[] args)
- {
- SqlConnection conn </span>= <span style="color: #0000ff;">new</span> SqlConnection(<span style="color: #800000;">"</span><span style="color: #800000;">server=.;database=mydb;uid=sa;pwd=123</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- conn.Open();
- SqlCommand cmd </span>=<span style="color: #000000;"> conn.CreateCommand();
- cmd.CommandText </span>= <span style="color: #800000;">"</span><span style="color: #800000;">delete from info where code=‘p005‘</span><span style="color: #800000;">"</span><span style="color: #000000;">;
- cmd.ExecuteNonQuery();
- conn.Close();
- }</span>
连接数据库查询数据
- <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">void</span> Main(<span style="color: #0000ff;">string</span><span style="color: #000000;">[] args)
- {
- SqlConnection conn </span>= <span style="color: #0000ff;">new</span> SqlConnection(<span style="color: #800000;">"</span><span style="color: #800000;">server=.;database=mydb;uid=sa;pwd=123</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- conn.Open();
- SqlCommand cmd </span>=<span style="color: #000000;"> conn.CreateCommand();
- cmd.CommandText </span>= <span style="color: #800000;">"</span><span style="color: #800000;">select * from info</span><span style="color: #800000;">"</span><span style="color: #000000;">;
- SqlDataReader r </span>= cmd.ExecuteReader();<span style="color: #008000;">//</span><span style="color: #008000;">查询语句用ExecuteReader返回SqlDataReader类</span>
- <span style="color: #0000ff;">while</span><span style="color: #000000;"> (r.Read())
- {
- Console.WriteLine(r[</span><span style="color: #800080;">0</span>].ToString()+r[<span style="color: #800080;">1</span>].ToString()+r[<span style="color: #800080;">2</span><span style="color: #000000;">].ToString());
- }
- conn.Close();
- }</span>
案例:用户登录实现
- <span style="color: #0000ff;">public</span> <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">void</span> Main(<span style="color: #0000ff;">string</span><span style="color: #000000;">[] arges)
- {
- Console.Write(</span><span style="color: #800000;">"</span><span style="color: #800000;">用户名:</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- </span><span style="color: #0000ff;">string</span> uid =<span style="color: #000000;"> Console.ReadLine();
- Console.Write(</span><span style="color: #800000;">"</span><span style="color: #800000;">密码:</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- </span><span style="color: #0000ff;">string</span> pwd =<span style="color: #000000;"> Console.ReadLine();
- SqlConnection conn </span>= <span style="color: #0000ff;">new</span> SqlConnection(<span style="color: #800000;">"</span><span style="color: #800000;">server=.;database=mydb;uid=sa;pwd=123</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- conn.Open();
- SqlCommand cmd </span>=<span style="color: #000000;"> conn.CreateCommand();
- cmd.CommandText </span>= <span style="color: #800000;">"</span><span style="color: #800000;">select * from login where username=‘</span><span style="color: #800000;">"</span>+uid+<span style="color: #800000;">"</span><span style="color: #800000;">‘ and password=‘</span><span style="color: #800000;">"</span>+pwd+<span style="color: #800000;">"</span><span style="color: #800000;">‘</span><span style="color: #800000;">"</span><span style="color: #000000;">;
- SqlDataReader r </span>=<span style="color: #000000;"> cmd.ExecuteReader();
- </span><span style="color: #0000ff;">if</span> (r.HasRows == <span style="color: #0000ff;">false</span><span style="color: #000000;">)
- {
- Console.WriteLine(</span><span style="color: #800000;">"</span><span style="color: #800000;">嗯哼,不对</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- }
- </span><span style="color: #0000ff;">else</span><span style="color: #000000;">
- {
- Console.WriteLine(</span><span style="color: #800000;">"</span><span style="color: #800000;">嗯哼,正确</span><span style="color: #800000;">"</span><span style="color: #000000;">);
- }
- conn.Close();
- }<br></span>
*** .HasRows()与.read()区别:HasRows只关系读数据库中的数据是否可行,而不执行读的操作.Read是执行读的操作看是否执行成功.二者都返回一个bool行的变量.***
C#连接数据库-曾,删,改,查
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