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.

GetCount

GetCount returns an integer count of records in a table that match a given SimpleExpression.

Syntax

public int GetCount(
		SimpleExpression criteria
	)

Parameters

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

Return Value

Type: int
A number that represents how many records in the table satisfy the conditions in the SimpleExpression.

Exceptions

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

Remarks

The GetCount method is used instead of GetCountBy 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 number of records in the Albums table with GenreId equal to 1.

int albumCount = Database.Open().Albums.GetCount(db.Albums.GenreId == 1);

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

select COUNT(*) from [dbo].[Albums] 
WHERE 
   [dbo].[Albums].[GenreId] = @p1
@p1 (Int32) = 1

Two Criteria

The following example retrieves the number of records in the Albums table with GenreId equal to 1 and ArtistId equal to 120.

int albumCount = Database.Open().Albums
   .GetCount(db.Albums.GenreId == 1 && db.Albums.ArtistId == 120);

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

select COUNT(*) from [dbo].[Albums] 
WHERE 
    ([dbo].[Albums].[GenreId] = @p1 AND [dbo].[Albums].[ArtistId] = @p2)
@p1 (Int32) = 1
@p2 (Int32) = 120