Exists

This method checks whether matching rows exist in a table.

Code Snippets

The following example checks whether a row exists in the [dbo].[Person] table by primary key.

using (var connection = new SqlConnection(connectionString))
{
    var existing = connection.Exists<Person>(10045);
}

A LINQ expression can also be used:

using (var connection = new SqlConnection(connectionString))
{
    var existing = connection.Exists<Person>(e =>
        e.Name == "Doe" && e.DateOfBirth =  DateTime.Parse("2000-01-01"));
}

Targeting a Table

To target a specific table, pass the literal table name.

using (var connection = new SqlConnection(connectionString))
{
    var existing = connection.Exists("[dbo].[Person]", 10045);
}

Use QueryGroup or QueryField to build more complex expressions.

using (var connection = new SqlConnection(connectionString))
{
    var where = new []
    {
        new QueryField("Name", "Doe"),
        new QueryField("DateOfBirth", DateTime.Parse("2000-01-01"))
    };
    var existing = connection.Exists("[dbo].[Person]", where);
}

Table Hints

Pass a table hint via the hints argument.

using (var connection = new SqlConnection(connectionString))
{
    var existing = connection.Exists<Person>(10045,
    hints: "WITH (NOLOCK)");
}

Or use the SqlServerTableHints class.

using (var connection = new SqlConnection(connectionString))
{
    var existing = connection.Exists<Person>(10045,
    hints: SqlServerTableHints.NoLock);
}