Hua Gong retries and study notes, Hua Gong Study Notes

Hua Gong retries and study notes, Hua Gong Study Notes

Today is July 22, March 10, and there are 5 days before the review of the Chinese site. the Retest is performed on the database, and the questions are given by VS and SQL server. difficult. below are my notes for testing the machine.

I. Database Design

Create index <index-name> on <relation-name> (<attribute-list>)

Example: create index dept-index on policuctor (dept_name)

Create view v as <query-expression>

Example: create view faulty

Select ID, name, dept_name

From instructor

Default 0

Check (P) // P is the condition

For example, check (size <10) // only records with a size smaller than 10 can be inserted.

Foreign key (dept_name) references department

On delete cascade

On update cascade

 

SELECT field FROM table WHERE a field Like Condition

 

Condition:

① %: 0 or more characters.

② _: Represents any single character.

③ []: Indicates one of the characters listed in brackets (similar to regular expressions ).

④ [^]: A single character not listed in parentheses.

⑤ When the query content contains wildcards: use [] to enclose special characters.

 

Ii. Database Programming

Server = <IP>; Database = <Database Name>; Integrated Security = false; Uid = <Login Name>; Pwd = <password>

Server = (local); Database = <Database Name>; Integrated Security = sspi

 

 

Public static void ExecuteNoQuery (string SQL)

{

Try

{

SqlCommand cmd = new SqlCommad (SQL, SqlUtil. conn );

If (cmd. ExcuteNoQuery ()> 0)

{

MessageBox. Show ("operation successful ");

}

Else

{

MessageBox. Show ("Operation failed ");

}

}

Catch (Exception ex)

{

MessageBox. Show (ex. Message );

}

 

}

 

 

Public static DataTable ExecuteQuery (string SQL)

{

Try

{

DataTable table = new DataTable ();

DataAdapter adapter = new DataAdapter (SQL, SqlUtil. conn );

Adapter. Fill (table );

Return table;

}

Catch (Exception ex)

{

MessageBox. Show (ex. Message );

Return null;

}

}

 

 

Try

{

SqlConnection conn = new SqlConnection (SqlUtil. connstr );

Conn. Open ();

}

Catch (Exception ex)

{

MessageBox. Show (ex. Message );

Applitcation. Exit ();

Return;

}

 

SqlUtil. conn. Close (); // do not use Dispose () because the connection resources will be recycled.

 

DataGridView1.DataSource = table;

 

SelectedIndexChanged

 

This. dataGridView1.SelectedRows [0]. Cell [0]. Value;

 

DataGridView1.Rows. RemoveAt (maid [0]. index );

 

DataGridView1.SelectionMode = maid mode. FullRowSelect;

 

DataGridView1.ReadOnly = true;

 

DialogResult dr = MessageBox. Show (this, "are you sure you want to delete ?"," Prompt ", MessageBoxButton. YesNO );

If (dr = DialogResult. Yes) // The code after clicking OK

 

Activated

 

Private void refresh ()

{

String SQL = "select * from <Table Name> ";

DataTable table = SqlUtil. ExecuteQuery (SQL );

DataGridView1.DataSource = table;

}