Class Default

Namespace

YndigoBlue.Velocity.Constraints

Assembly

YndigoBlue.Velocity.dll

Represents a default value constraint that automatically assigns a value to a column when no value is specified during insert.

public class Default : Constraint, IEquatable<Constraint>, IComparable<Constraint>

Inheritance

object

Constraint

Default

Implements

IEquatable<Constraint>

IComparable<Constraint>

Remarks

Default constraints provide automatic values for columns, such as timestamps, sequential numbers, or constant values. They are applied when INSERT statements don't provide explicit values for the column.

Examples

using (var manager = new Manager(connection))
{
    var schema = manager.LoadSchema("myschema");
    Table table = schema.CreateTable("orders");
    table.CreateColumn("id", DataType.Integer, autoGenerate: true);
    table.CreateColumn("status", DataType.VarChar, size: 20);
    table.CreateColumn("created_at", DataType.DateTime);
    table.CreateColumn("is_active", DataType.Boolean);
    table.CreateColumn("priority", DataType.Integer);

    // Default string value
    Default defaultStatus = table.CreateDefaultConstraint("status",
        new Literal<string>("Pending"), DefaultConstraintType.String, DataType.VarChar);

    // Default to current timestamp using the Now() function
    Default defaultCreatedAt = table.CreateDefaultConstraint("created_at",
        new Now(), DefaultConstraintType.Function, DataType.DateTime);

    // Default boolean value
    Default defaultActive = table.CreateDefaultConstraint("is_active",
        new Literal<bool>(true), DefaultConstraintType.Boolean, DataType.Boolean);

    // Default numeric value
    Default defaultPriority = table.CreateDefaultConstraint("priority",
        new Literal<double>(1.0D), DefaultConstraintType.Number, DataType.Integer);

    manager.CreateTable(table);
    manager.CreateConstraint(defaultStatus);
    manager.CreateConstraint(defaultCreatedAt);
    manager.CreateConstraint(defaultActive);
    manager.CreateConstraint(defaultPriority);
}

Properties

Column

Gets the name of the column that this default constraint applies to.

ConstraintType

Gets the constraint type as Default.

DataType

Gets the data type of the column.

DefaultConstraintType

Gets the type of default constraint (String, Number, DateTime, Date, Timestamp, Boolean, or Guid).

DefaultItem

Gets the default value item (can be a literal value, function call, or expression).

Methods

IsEqual(Constraint)

Determines whether this constraint is equal to another constraint based on their properties.