Tài liệu Creating a New SQL Server Database doc

[ Team LiB ]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

[ Team LiB ]

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 of 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:

Database 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

Database 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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