Class Criterion<T>

Namespace: YndigoBlue.Velocity.Model

Assembly: YndigoBlue.Velocity.dll

Represents a single comparison criterion in a WHERE or HAVING clause.

public class Criterion<T> : IFilterItem, ICriterion

Type Parameters

T: The data type of the value being compared. Common types include: string, int, long, decimal, DateTime, bool, Query (for subqueries), Column (for column comparisons).

Inheritance: object

Criterion<T>

Implements: IFilterItem

ICriterion

Examples

Simple equality:

// WHERE firstname = 'John'
Criterion<string> criterion = new Criterion<string>(
    usersTable["firstname"],
    ConditionalType.Equals,
    "John"
);

Comparison operators:

// WHERE age > 30
Criterion<int> ageCriterion = new Criterion<int>(
    usersTable["age"],
    ConditionalType.GreaterThan,
    30
);

IN clause with multiple values:

// WHERE status IN ('active', 'pending', 'approved')
List<string> statusValues = new List<string> { "active", "pending", "approved" };
Criterion<string> statusCriterion = new Criterion<string>(
    usersTable["status"],
    ConditionalType.In,
    statusValues
);

BETWEEN clause:

// WHERE age BETWEEN 18 AND 65
List<int> ageRange = new List<int> { 18, 65 };
Criterion<int> ageCriterion = new Criterion<int>(
    usersTable["age"],
    ConditionalType.Between,
    ageRange
);

Subquery criterion:

// WHERE age > (SELECT AVG(age) FROM users)
Query avgAgeQuery = new Query();
avgAgeQuery.AddFromItem(usersTable);
avgAgeQuery.AddSelectItem(new Function(FunctionType.Avg, usersTable["age"]));
Criterion<Query> ageCriterion = new Criterion<Query>(
    usersTable["age"],
    ConditionalType.GreaterThan,
    avgAgeQuery
);

NULL checks:

// WHERE deleted_at IS NULL
Criterion<object> nullCriterion = new Criterion<object>(
    usersTable["deleted_at"],
    ConditionalType.IsNull
);

Remarks

Criterion is the fundamental building block for query filters. Each criterion represents a single comparison operation such as "age > 30" or "status = 'active'".

The generic type parameter determines the comparison value type: