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Query Expressions


This page contains the recommended way of using the query expressions when fetching/pushing the data from/to the database.

Disclaimer

The support to query objects are massive and well tested with high-quality. However, the Linq-Expression parser of the library is not as extensive as Entity Framework. Therefore, we highly recommend to always use the QueryGroup and QueryField objects when composing a complex expressions.

Equal

Via Dynamic:

var result = connection.Query<Customer>(new { Id = 10045 });

The query via dynamic object is only supporting the Equal operation.

Via Expression:

var result = connection.Query<Customer>(e => e.Id == 10045);

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Id", Operation.Equal, 10045));

NotEqual

Via Expression:

var result = connection.Query<Customer>(e => e.Name != "Anna Fullerton");

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Name", Operation.NotEqual, "Anna Fullerton" });

LessThan

Via Expression:

var result = connection.Query<Customer>(e => e.Id < 100);

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Id", Operation.LessThan, 100 });

GreaterThan

Via Expression:

var result = connection.Query<Customer>(e => e.Id > 100);

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Id", Operation.GreaterThan, 100 });

LessThanOrEqual

Via Expression:

var result = connection.Query<Customer>(e => e.Id <= 100);

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Id", Operation.LessThanOrEqual, 100 });

GreaterThanOrEqual

Via Expression:

var result = connection.Query<Customer>(e => e.Id >= 0);

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Id", Operation.GreaterThanOrEqual, 0 });

Like

There are various combinations.

Contains

Via Expression:

var result = connection.Query<Customer>(e => e.Name.Contains("Anna"));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Name", Operation.Like, "%Anna%" });

StartsWith

Via Expression:

var result = connection.Query<Customer>(e => e.Name.StartsWith("Anna"));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Name", Operation.Like, "Anna%" });

EndsWith

Via Expression:

var result = connection.Query<Customer>(e => e.Name.EndsWith("Anna"));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Name", Operation.Like, "%Anna" });

NotLike

There are various combinations.

Contains

Via Expression:

var result = connection.Query<Customer>(e => !e.Name.Contains("Anna"));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Name", Operation.NotLike, "%Anna%" });

StartsWith

Via Expression:

var result = connection.Query<Customer>(e => !e.Name.StartsWith("Anna"));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Name", Operation.NotLike, "Anna%" });

EndsWith

Via Expression:

var result = connection.Query<Customer>(e => !e.Name.EndsWith("Anna"));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Name", Operation.NotLike, "%Anna" });

Between

Via Expression:

var result = connection.Query<Customer>(e => e.Id >= 10045 && e.Id <= 10075));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Id", Operation.Between, new [] { 10045, 10075 } ));

NotBetween

Via Expression:

var result = connection.Query<Customer>(e => e.Id <= 10045 && e.Id >= 10075));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Id", Operation.NotBetween, new [] { 10045, 10075 } ));

In

Via Expression:

var keys = new[] { 10045, 10046, 10047, 10048 };
var result = connection.Query<Customer>(e => keys.Contains(e.Id)));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Id", Operation.In, new [] { 10045, 10046, 10047, 10048 }));

NotIn

Via Expression:

var keys = new[] { 10045, 10046, 10047, 10048 };
var result = connection.Query<Customer>(e => !keys.Contains(e.Id)));

Via QueryField.

var result = connection.Query<Customer>(new QueryField("Id", Operation.NotIn, new [] { 10045, 10046, 10047, 10048 }));

Complex Expressions

As mentioned in the disclaimer above, do not to do this.

var result = connection.Query<Customer>(e => (e.IsActive == true && (e.DateInserted >= Yesterday && e.DateInserted <= Today) && (new[] { "Washington", "New York", "California" }).Contains(e.State)) ||
    (e.IsActive == false && (e.DateInserted >= LastMonth && e.DateInserted <= Yesterday) && (new[] { "Washington", "New York", "California" }).Contains(e.State));

We will support the complex Linq-expression soon. But, until further notice, please use the query objects when composing complex expressions.

Instead, do this.

// Left Or
var whereActive = new QueryField("IsActive", true);
var whereDate = new QueryField("DateInserted", Operation.Between, new [] { Yesterday, Today });
var whereState = new QueryField("State", Operation.In, new [] { "Washington", "New York", "California" });

// Right Or
var whereActiveRight = new QueryField("IsActive", false);
var whereDateRight = new QueryField("DateInserted", Operation.Between, new [] { LastMonth, Yesterday });
var whereStateRight = new QueryField("State", Operation.In, new [] { "Washington", "New York", "California" });

// Expression
var leftGrouping = new QueryGroup(new [] { whereActive, whereDate, whereState });
var rightGrouping = new QueryGroup(new [] { whereActiveRight, whereDateRight, whereStateRight });
var where = new QueryGroup(new [] { leftGrouping, rightGrouping }, Conjunction.Or);

// Query
var result = connection.Query<Customer>(where));

Will generate the SQL below.

> WHERE (([IsActive] = @IsActive1 AND [DateInserted] BETWEEN @Date1 AND @Date2 AND [State] IN (@State1, @State2, @State3) OR ([IsActive] = @IsActive2 AND [DateInserted] BETWEEN @Date3 AND @Date4 AND [State] IN (@State4, @State5, @State6))