Interface IQuery<T>

Interface, which describe class for executing query.

Instance which implement this interface can be used for creating and executing query for T model.

Inherited Members
Namespace: Kros.KORM.Query
Assembly: Kros.KORM.dll
Syntax
public interface IQuery<T> : IProjectionQuery<T>, IQueryBase<T>, IOrderedQueryable<T>, IQueryable<T>, IEnumerable<T>, IOrderedQueryable, IQueryable, IEnumerable
Type Parameters
Name Description
T

Type of model class.
Remarks

When you don't use Select or From function, than default values are taken from model.

Examples

You can use standard string sql query for querying data. 

                var people = database.Query<Person>().Sql(
            "SELECT p.Id, FirstName, LastName, PostCode " +
            "FROM Person " +
            "JOIN Address ON (Person.AddressId = Address.Id) " +
            "WHERE Age > @1", 18);

        foreach (var person in people)
        {
            Console.WriteLine(person.FirstName);
        }

You can use sql query builder. 

                var people = database.Query<Person>()
            .Select("p.Id", "FirstName", "LastName", "PostCode")
            .From("Person JOIN Address ON (Person.AddressId = Address.Id)")
            .Where("Age > @1", 18);

        foreach (var person in people)
        {
            Console.WriteLine(person.FirstName);
        }

Methods

From(String)

Add FROM part to sql query.

Declaration
IProjectionQuery<T> From(string table)
Parameters
Type Name Description
System.String table

Table name or join.
Returns
Type Description
IProjectionQuery<T>

Query for enumerable models.
Remarks

When From method is not call, query take table by T model type.

Examples
                var people = database.Query<Person>().From("Person LEFT JOIN Avatar ON (Person.Id = Avatar.PersonId)");
Exceptions
Type Condition
System.ArgumentNullException

if table is null or white string.

Select(String)

Add select part to sql.

Declaration
IQuery<T> Select(string selectPart)
Parameters
Type Name Description
System.String selectPart

The columns for select clausule. (Separate by ,)
Returns
Type Description
IQuery<T>

Query for enumerable models.
Remarks

When Select method is not call, query take columns by T model.

Examples
                var people = database.Query<Person>().Select("Id, FirstName");
Exceptions
Type Condition
System.ArgumentNullException

if sqlPart is null or white string.

Select(String[])

Add columns to sql.

Declaration
IQuery<T> Select(params string[] columns)
Parameters
Type Name Description
System.String[] columns

The columns for select clausule.
Returns
Type Description
IQuery<T>

Query for enumerable models.
Remarks

When Select method is not call, query take columns by T model.

Examples
                var people = database.Query<Person>().Select("Id", "FirstName");

Select<TResult>(Func<T, TResult>)

Add columns to sql

Declaration
IQuery<T> Select<TResult>(Func<T, TResult> selector)
Parameters
Type Name Description
System.Func<T, TResult> selector

The selector.
Returns
Type Description
IQuery<T>

Query for enumerable models.
Type Parameters
Name Description
TResult

The type of the result.
Remarks

When Select method is not call, query take columns by T model.

Examples
                var people = database.Query<Person>().Select(p => new { p.Id, p.FirstName });
Exceptions
Type Condition
System.ArgumentNullException

if selector is null.

Sql(RawSqlString, Object[])

Create query from sql statement.

Declaration
IQueryBase<T> Sql(RawSqlString sql, params object[] args)
Parameters
Type Name Description
RawSqlString sql

The SQL for executing in server.
System.Object[] args

The arguments.
Returns
Type Description
IQueryBase<T>

Query from sql.
Remarks

Sql must be server specific. Because no translation is provide.

Exceptions
Type Condition
System.ArgumentNullException

if sql is null or white string.

Sql(FormattableString)

Create query from sql statement.

Declaration
IQueryBase<T> Sql(FormattableString sql)
Parameters
Type Name Description
System.FormattableString sql

The SQL for executing in server.
Returns
Type Description
IQueryBase<T>

Query from sql.
Remarks

Sql must be server specific. Because no translation is provide.

Examples
var id = 15;
var name = "Name";
var items = query.Sql($"SELECT * FROM Table WHERE Id = {id} AND Name = {name}");
Exceptions
Type Condition
System.ArgumentNullException

if sql is null or white string.

See Also