Tài liệu Creating a New SQL Server Database doc

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Recipe 10.7 Creating a New SQL Server Database
Problem
You need to create a new database in your SQL Server.
Solution
Use the CREATE DATABASE statement.
The sample code executes the DDL statement—using the ExecuteNonQuery( ) method o
f

the Command object—to create a new database named MyDatabase in SQL Server.
The C# code is shown in Example 10-7
.
Example 10-7. File: CreateServerDatabaseForm.cs
// Namespaces, variables, and constants
using System;
using System.Configuration;
using System.Text;
using System.Data;
using System.Data.SqlClient;

// . . .

StringBuilder sb = new StringBuilder( );

// SQL DDL command text to create database.
String sqlText = "CREATE DATABASE MyDatabase ON PRIMARY " +
"(NAME = MyDatabase_Data, " +

"FILENAME = '" + DATAFILENAME + "', " +
"SIZE = 2MB, MAXSIZE = 10MB, FILEGROWTH = 10%) " +
"LOG ON (NAME = MyDatabase_Log, " +
"FILENAME = '" + LOGFILENAME + "', " +
"SIZE = 1MB, " +
"MAXSIZE = 5MB, " +
"FILEGROWTH = 10%)";

sb.Append(sqlText + Environment.NewLine + Environment.NewLine);

// Create a connection.
SqlConnection conn = new SqlConnection(
ConfigurationSettings.AppSettings["Sql_Master_ConnectString"]);

// Create the command to create the database.
SqlCommand cmd = new SqlCommand(sqlText, conn);
// Create the new database.
try
{
conn.Open( );
cmd.ExecuteNonQuery( );
sb.Append("DataBase created successfully.");
}
catch (System.Exception ex)
{
sb.Append(ex.ToString( ));
}
finally
{
if (conn.State == ConnectionState.Open)

conn.Close( );
conn.Close( );
}

resultTextBox.Text = sb.ToString( );
Discussion
There are two categories of SQL statements:
D
atabase Definition Language (DDL)
Used to manage all objects in the database, generally with CREATE, ALTER, and
DROP statements to create, modify, and delete objects, respectively. These
statements generally require DBA permissions to execute.
D
atabase Management Language (DML)
Used to manipulate—select, insert, update, and delete—data in the database
objects. Database objects are defined using DDL.
The solution executes a DDL CREATE DATABASE statement to create a new database
on a SQL Server.
You can programmatically drop the database by using the DROP DATABASE statement
in a similar way. To drop the database created in the previous example, use the following
code:
DROP DATABASE MyDatabase
The DROP DATABASE statement will fail if the database is in use; therefore, it might
be necessary to restart the SQL Server in order to drop the database. System databases—
master, model, msdb, and tempdb—cannot be dropped.
For more information about the CREATE DATABASE statement, the DROP
DATABASE statement, or DDL, see Microsoft SQL Server Books Online.
The solution for Oracle databases and other databases is similar to that shown for SQL
Server although the DDL syntax for each database varies slightly because of differences
in database server capabilities and architecture. For more information about Oracle SQL

syntax, see Oracle in a Nutshell (O'Reilly).
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