Simple.Data

Simple.Data defines a number of commands for retrieving data from a data store. These can then be daisychained in a LINQ-like fashion with further methods to modify the basic query.

Find

Find returns a single row of data as a SimpleRecord object based on a SimpleExpression defining the criteria for the search; if more than one row matches, the first row retrieved from the data store is returned.

Syntax

public SimpleRecord Find(
		SimpleExpression criteria
	)

Parameters

criteria: Type: SimpleExpression
A (concatenated sequence of) search criteria. For example, dbo.Album.GenreId == 1.

Return Value

Type: SimpleRecord
An object containing a property for each of the columns requested by Simple.Data whose values are those of the single row retrieved from the data store.

Exceptions

Exception	Condition
`FormatException` - or - `BadExpressionException`	`criteria`is a malformed `SimpleExpression`
`BadExpressionException`	`criteria` has been assigned zero or more than one `SimpleExpression`

Remarks

The Find method is used instead of FindBy when the criteria is more complicated than simple equality tests. Criteria can be constructed just using regular C# expressions, with all operators supported and precedence-grouping honoured.

These C# expressions are represented internally as a SimpleExpression object. For more on SimpleExpressions, please read this page. Read also the Column Selection page for more on how to identify the columns in a SimpleExpression.

Examples

One Criteria

The following example retrieves the first album with GenreId equal to 1 and outputs its title to the Console window.

var album = Database.Open().Albums.Find(db.Albums.GenreId == 1);
Console.WriteLine(album.Title);

Simple.Data sends the following SQL to the database when album is evaluated.

SELECT TOP 1 
    [dbo].[Album].[AlbumId], 
    [dbo].[Album].[GenreId], 
    [dbo].[Album].[ArtistId], 
    [dbo].[Album].[Title], 
    [dbo].[Album].[Price], 
    [dbo].[Album].[AlbumArtUrl] 
from [dbo].[Album]  
where 
    [dbo].[Album].[GenreId] = @p1
@p1 (Int32) = 1

Two Criteria

The following example retrieves the first album with GenreId equal to 1 and ArtistId equal to 120 and outputs its title to the Console window.

var album = Database.Open().Albums
   .Find(db.Albums.GenreId == 1 && db.Albums.ArtistId == 120);	
Console.WriteLine(album.Title);

Simple.Data sends the following SQL to the database when album is evaluated.

SELECT TOP 1 
    [dbo].[Album].[AlbumId], 
    [dbo].[Album].[GenreId], 
    [dbo].[Album].[ArtistId], 
    [dbo].[Album].[Title], 
    [dbo].[Album].[Price], 
    [dbo].[Album].[AlbumArtUrl] 
from [dbo].[Album]  
where 
    ([dbo].[Album].[GenreId] = @p1 AND [dbo].[Album].[ArtistId] = @p2)
@p1 (Int32) = 1
@p2 (Int32) = 120

One Criteria Or Another

The following example retrieves the first album with GenreId greater than 2 or ArtistId less than or equal to 200 and outputs its title to the Console window.

var album = Database.Open().Albums
   .Find(db.Albums.GenreId > 2 || db.Albums.ArtistId <= 200);	
Console.WriteLine(album.Title);

Simple.Data sends the following SQL to the database when album is evaluated.

SELECT TOP 1 
    [dbo].[Album].[AlbumId], 
    [dbo].[Album].[GenreId], 
    [dbo].[Album].[ArtistId], 
    [dbo].[Album].[Title], 
    [dbo].[Album].[Price], 
    [dbo].[Album].[AlbumArtUrl] 
from [dbo].[Album]  
where 
    ([dbo].[Album].[GenreId] > @p1 OR [dbo].[Album].[ArtistId] <= @p2)
@p1 (Int32) = 2
@p2 (Int32) = 200