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>

Examples

// Define a table with default value constraints
var table = new Table(schema, "orders");
table.AddColumn("id", DataType.Integer, autoIncrement: true);
table.AddColumn("customer_id", DataType.Integer);
table.AddColumn("order_date", DataType.DateTime);
table.AddColumn("status", DataType.VarChar, 20);
table.AddColumn("created_at", DataType.DateTime);

// Create default constraint for current timestamp on created_at
var defaultCreatedAt = new Default(
    schema.Name,
    "orders",
    "created_at",
    new Literal<DateTime>(DateTime.Now),
    DefaultConstraintType.DateTime,
    DataType.DateTime
);

// Create default constraint for status
var defaultStatus = new Default(
    schema.Name,
    "orders",
    "status",
    new Literal<string>("Pending"),
    DefaultConstraintType.String,
    DataType.VarChar
);

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.

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

GetColumnsForComparison()

Gets columns for comparison in a name-neutral way. Override in subclasses that have columns.

IsEqual(Constraint)

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