mirror of
https://github.com/m-lamonaca/dev-notes.git
synced 2025-04-05 18:36:41 +00:00
113 lines
4.1 KiB
Markdown
113 lines
4.1 KiB
Markdown
# [ADO.NET](https://docs.microsoft.com/en-us/dotnet/framework/data/adonet/ "ADO.NET Docs")
|
|
|
|
`ADO.NET` is a set of classes that expose data access services for .NET.
|
|
The `ADO.NET` classes are found in `System.Data.dll`, and are integrated with the XML classes found in `System.Xml.dll`.
|
|
|
|
[ADO.NET provider for SQLite](https://system.data.sqlite.org/index.html/doc/trunk/www/index.wiki "System.Data.SQLite")
|
|
|
|
## [Connection Strings](https://www.connectionstrings.com)
|
|
|
|
### [SQL Server 2019](https://www.connectionstrings.com/sql-server-2019/)
|
|
|
|
- Standard Security:
|
|
- `Server=<server_name>; Database=<database>; UID=<user>; Pwd=<password>;`
|
|
- `Server=<server_name>; Database=<database>; User ID=<user>; Password=<password>;`
|
|
- `Data Source=<server_name>; Initial Catalog=<database>; UID=<user>; Pwd=<password>;`
|
|
- Specific Instance: `Server=<server_name>\<instance_name>; Database=<database>; User ID=<user>; Password=<password>;`
|
|
- Trusted Connection (WinAuth): `Server=<server_name>; Database=<database>; Trusted_Connection=True;`
|
|
- MARS: `Server=<server_name>; Database=<database>; Trusted_Connection=True; MultipleActiveResultSets=True;`
|
|
|
|
> **Note**: *Multiple Active Result Sets* (MARS) is a feature that works with SQL Server to allow the execution of multiple batches on a single connection.
|
|
|
|
### [SQLite](https://www.connectionstrings.com/sqlite/)
|
|
|
|
- Basic: `Data Source: path\to\db.sqlite3; Version=3;`
|
|
- In-Memory Database: `Data Source=:memory:; Version=3; New=True`
|
|
- With Password: `Data Source: path\to\db.sqlite3; Version=3; Password=<password>`
|
|
|
|
## Connection to DB
|
|
|
|
```cs
|
|
using System;
|
|
using System.Data.SqlClient; // ADO.NET Provider, installed through NuGet
|
|
|
|
namespace <namespace>
|
|
{
|
|
class Program
|
|
{
|
|
static void Main(string[] args)
|
|
{
|
|
// Connection to SQL Server DBMS
|
|
SqlConnectionStringBuilder connectionString = new SqlConnectionStringBuilder();
|
|
connectionString.DataSource = "<server_name>";
|
|
connectionString.UserID = "<user>";
|
|
connectionString.Password = "<password>";
|
|
connectionString.InitialCatalog = "<database>";
|
|
|
|
// more compact
|
|
SqlConnectionStringBuilder connectionString = new SqlConnectionStringBuilder("Server=<server_name>;Database=<database>;UID=<user>;Pwd=<password>")
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
## DB Interrogation
|
|
|
|
### `SqlConnection`
|
|
|
|
```cs
|
|
using (SqlConnection connection = new SqlConnection())
|
|
{
|
|
connection.ConnectionString = connectionString.ConnectionString;
|
|
connection.Open(); // start communication w/ sql server
|
|
}
|
|
|
|
// more compact
|
|
using (SqlConnection connection = new SqlConnection(connectionString)) {
|
|
connection.Open()
|
|
}
|
|
```
|
|
|
|
### [SqlCommand](https://docs.microsoft.com/en-us/dotnet/api/system.data.sqlclient.sqlcommand)
|
|
|
|
```cs
|
|
string sql = "<sql_instruction>";
|
|
|
|
using (SqlCommand command = new SqlCommand())
|
|
{
|
|
command.Connection = connection; // SqlConnection
|
|
command.CommandText = "... @Parameter"; // or name of StoredProcedure
|
|
|
|
// add parameters to the SqlParameterCollection, WARNING: table names or columns cannot be parameters
|
|
command.Parameters.Add("@Parameter", SqlDbType.<DBType>, columnLength).Value = value;
|
|
command.Parameters.AddWithValue("@Parameter", value);
|
|
command.Parameters.AddWithValue("@Parameter", (object) value ?? DBNull.Value); // if Parameter is nullable
|
|
|
|
// Create an instance of a SqlParameter object.
|
|
command.CreateParameter();
|
|
|
|
command.CommandType = CommandType.Text; // or StoredProcedure
|
|
|
|
int affectedRows = command.ExecuteNonQuery(); // execute the query and return the number of affected rows
|
|
}
|
|
```
|
|
|
|
### `SqlDataReader`
|
|
|
|
```cs
|
|
using (SqlDataReader cursor = command.ExecuteReader()) // object to get data from db
|
|
{
|
|
while (cursor.Read()) // get data till possible
|
|
{
|
|
// preferred methodology
|
|
cursor["<column_name>"].ToString(); // retrieve data form the column
|
|
cursor[<column_index>].ToString(); // retrieve data form the column
|
|
|
|
// check for null before retrieving the value
|
|
if(!cursor.IsDBNull(n))
|
|
{
|
|
cursor.Get<SystemType>(index); // retrieve data form the n-th column
|
|
}
|
|
}
|
|
}
|
|
```
|