DataTable C#

C# > System.Data   > DataTable

DataTable is a table in memory data.
When accessing DataTable objects in DataSet they are case sensitive.
We can display data from it  in controls such as DataGridView.

Properties:

Columns:         collection of columns
Rows:              collection of rows
DefaultView:   customized view of the table that may include a filtered view, or a cursor position.


Example:

   Create a new DataTable   

    System.Data.DataTable table = new DataTable("myTable");

Other examples:

• Add columns to DataTable
• Fill from DataBase
• Filter with LINQ
• Max value of column

System.Data namespace C#

C# > System.Data

System.Data namespace contains classes that represent ADO.NET architecture.
ADO.NET efficiently manages data from multiple data sources.

• DataTable
• SqlCommand
• DataSet
• OleDb
• SqlClient

Examples:

1. Populating DataSet and DataTable

Add Columns to DataTable C#

C# > DataTable  > Add  column

Using Columns collection we can add columns to DataTable in runtime.

Example:

DataTable dt = new DataTable("Product");

dt.Columns.Add("id",typeof(Int32));
dt.Columns.Add("name",typeof(string));

Oracle FOR LOOP

Oracle > FOR LOOP IN

The syntax for the FOR Loop In Oracle is:

FOR loop_counter IN [REVERSE] lowest_number..highest_number
LOOP
{.statements.}
END LOOP;

Example:

begin
  for i in 1..10 loop
    DBMS_OUTPUT.PUT_LINE (i);
   end loop ;
end ;
/

Microsoft SQL Server System Views

Microsoft SQL Server system views provides a collections of system views that expose metadata.

System Stored Procedures SQL Server

SQL Server > System Stored Procedures

Using system stored procedures you can perform many administrative and informational activities.

Catalog

• sp_databases
• sp_columns
• sp_tables
• sp_server_info

Extended

• xp_cmdshell

Mail

• sp_send_dbmail

Database Engine

• sp_who
• sp_dbremove
• sp_clean_db_free_space

sp_databases SQL Server

SQL Server > System Stored Procedures > sp_databases

sp_databases lists databases that reside in an instance of the SQL Server Database .

Example:

USE master;

GO
EXEC sp_databases;

DATABASE_NAME           DATABASE_SIZE               REMARKS

action_plan        4160       NULL
master  4864       NULL
model   2624       NULL
msdb     13312    NULL
tempdb                2560       NULL