C#数据库查询和操作大全

Posted 2020-08-14

一：C#数据库查询之数据库连接代码：

1. SqlConnectionobjSqlConnection=newSqlConnection("server=127.0.0.1;uid=sa;pwd=;database=test");  
2. objSqlConnection.Open(); 

二：数据库的添加记录代码：

1. inti=0;  
2. strings1="",s2="";  
3. i=Convert.ToInt16(textBox1.Text);  
4. s1=textBox2.Text;  
5. s2=textBox3.Text;  
6.  
7. SqlConnectionobjSqlConnection=newSqlConnection("server=127.0.0.1;uid=sa;pwd=;database=test");  
8. objSqlConnection.Open();  
9.  
10. MessageBox.Show("数据库连接成功","好");  
11.  
12. try  
13. {  
14. SqlCommandsqlcom=newSqlCommand("insertintoinfo(id,name,sex)values("+i+",‘"+s1+"‘,‘"+s2+"‘)",objSqlConnection);  
15. sqlcom.ExecuteNonQuery();  
16. MessageBox.Show("添加成功！","啊");  
17. }  
18. catch(Exceptiona)  
19. {  
20. MessageBox.Show(a.ToString());  
21. }  
22. MessageBox.Show("添加成功！","啊");  
23. } 

三：数据库的修改代码：

1. inti=0;  
2. strings1="",s2="";  
3. s1=textBox2.Text;  
4. s2=textBox3.Text;  
5. if(textBox1.Text.Length==0)  
6. i=0;  
7. else 
8. i=Convert.ToInt32(textBox1.Text);  
9.  
10. SqlConnectionobjSqlConnection=newSqlConnection("server=127.0.0.1;uid=sa;pwd=;database=test");  
11. objSqlConnection.Open();  
12. MessageBox.Show("数据库连接成功","好");  
13. try  
14. {  
15. SqlCommandsqlcom=newSqlCommand("updateinfosetname=‘"+s1+"‘,sex=‘"+s2+"‘"+"whereid="+i,objSqlConnection);  
16. sqlcom.ExecuteNonQuery();  
17. MessageBox.Show("修改成功！","啊");  
18. objSqlConnection.Close();  
19. }  
20. catch(Exceptiona)  
21. {  
22. MessageBox.Show(a.ToString());  
23. } 

四：数据库的删除代码：

1. inti=0;  
2. strings1="",s2="";  
3. s1=textBox2.Text;  
4. s2=textBox3.Text;  
5. if(textBox1.Text.Length==0)  
6. i=0;  
7. else 
8. i=Convert.ToInt16(textBox1.Text);  
9. SqlConnectionobjSqlConnection=newSqlConnection("server=127.0.0.1;uid=sa;pwd=;database=test");  
10. objSqlConnection.Open();  
11. MessageBox.Show("数据库连接成功","好");  
12. try 
13. {  
14. SqlCommandsqlcom=newSqlCommand("deletefrominfowhereid="+i,objSqlConnection);  
15.  
16. sqlcom.ExecuteNonQuery();  
17.  
18. MessageBox.Show("删除成功！","啊");  
19.  
20. objSqlConnection.Close();  
21. }  
22. catch(Exceptiona)  
23. {  
24. MessageBox.Show(a.ToString());  
25. } 

五：数据库的查询代码：

1.类开始：

1. DataTabledt1=newDataTable();  
2. SqlDataAdapterda1=newSqlDataAdapter(); 

2.按钮代码：

1. inti=0,n=0;  
2. strings1="",s2="";  
3. s1=textBox2.Text;  
4. s2=textBox3.Text;  
5. if(textBox1.Text.Length==0)  
6. i=0;  
7. else 
8. i=Convert.ToInt32(textBox1.Text);  
9. SqlConnectionobjSqlConnection=newSqlConnection("server=127.0.0.1;uid=sa;pwd=;database=test");  
10. objSqlConnection.Open();  
11. MessageBox.Show("数据库连接成功","好");  
12.  
13. stringquery="SELECT*frominfowhereid="+i;  
14.  
15. DataSetobjDataSet=newDataSet();  
16.  
17. SqlDataAdapterobj=newSqlDataAdapter();  
18.  
19. obj.SelectCommand=newSqlCommand(query,objSqlConnection);  
20.  
21. obj.Fill(objDataSet,"info");  
22.  
23. SqlCommandobjSqlCommand=newSqlCommand(query,objSqlConnection);  
24.  
25. SqlDataReaderobjSqlReader=objSqlCommand.ExecuteReader();  
26.  
27. while(objSqlReader.Read())  
28. {  
29. n+=1;  
30. MessageBox.Show("编号:"+objSqlReader.Getvalue(0)+"姓名:"+objSqlReader.Getvalue(1)+"性别"+objSqlReader.Getvalue(2));  
31. }  
32. if(n==0)  
33. MessageBox.Show("数据库中没有这样的记录！"); 

六：C#数据库查询代码：

1. inti=0;  
2. //intn=0;  
3. strings1="",s2="";  
4. stringsql;  
5. s1=textBox2.Text;  
6. s2=textBox3.Text;  
7.  
8. if(textBox1.Text.Length==0)  
9. {  
10. i=0;  
11.  
12. }  
13. else 
14. i=Convert.ToInt32(textBox1.Text);  
15. SqlConnectionobjSqlConnection=newSqlConnection("server=127.0.0.1;uid=sa;pwd=;database=test");  
16. objSqlConnection.Open();  
17. MessageBox.Show("数据库连接成功","好");  
18. stringquery="SELECT*frominfowhereid="+i;  
19. if(i==0)  
20. sql="select*frominfo";  
21. else 
22. sql="select*frominfowhereid="+i;  
23. da1=newSqlDataAdapter(sql,objSqlConnection);  
24. dt1.Clear();  
25. da1.Fill(dt1);  
26. dataGridView1.DataSource=dt1; 

C#数据库查询之数据库的封装类代码：

1. classDBClass  
2. {  
3.  
4. publicvoiddbclass(stringsql)  
5. {  
6. try 
7. {  
8. SqlConnectionsqlcon=newSqlConnection("server=127.0.0.1;uid=sa;pwd=;database=test");  
9. sqlcon.Open();  
10.  
11. SqlTransactionobjt=sqlcon.BeginTransaction();//事物开始  
12.  
13. SqlCommandsqlcom=newSqlCommand(sql,sqlcon);  
14.  
15. sqlcom.Transaction=objt;//将Command对象设置为事物处理的对象  
16.  
17. sqlcom.ExecuteNonQuery();  
18. objt.Commit();//提交事物  
19. sqlcon.Close();  
20. }  
21. catch(Exceptiona)  
22. {  
23. MessageBox.Show(a.ToString());  
24. }  
25.  
26. }  
27. }  
28. --db2数据库连接代码：  
29. stringstrcon="Provider=IBMDADB2;DataSource=hfzd;UserId=db2admin;Password=db2admin";  
30. //stringsql="select*fromADMINISTRATOR.HFZD";  
31. stringsql="deletefromADMINISTRATOR.HFZDwhereID=1";  
32. OleDbConnectionolecon=newOleDbConnection(strcon);  
33. olecon.Open();  
34. MessageBox.Show("数据库已连接上");  
35. dt.Clear();  
36. da=newOleDbDataAdapter(sql,olecon);  
37. da.Fill(dt);  
38. dataGridView1.DataSource=dt;  
39. olecon.Close();