Class Delete

Namespace: YndigoBlue.Velocity.Model

Assembly: YndigoBlue.Velocity.dll

Represents a DELETE statement for removing rows from a database table.

public class Delete

Inheritance: object

Delete

Examples

Delete with WHERE clause (most common):

using (Manager manager = new Manager(connection))
{
    manager.LoadSchema("my_schema");
    Schema schema = manager.GetSchema("my_schema");
    Table usersTable = schema["users"];

    // Delete inactive users
    Filter filter = new Filter(
        new Criterion<string>(usersTable["status"], "inactive")
    );
    Delete delete = new Delete(usersTable, filter);

    int rowsDeleted = manager.Delete(delete);
    Console.WriteLine($"Deleted {rowsDeleted} rows");
}

// SQL: DELETE FROM users WHERE status = 'inactive'

Delete with multiple conditions:

// Delete old inactive accounts
Filter filter = new Filter();
filter.Add(new Criterion<string>(usersTable["status"], "inactive"));
filter.Add(new BooleanItem(BooleanType.And));
filter.Add(new Criterion<DateTime>(
    usersTable["last_login"],
    ConditionalType.LessThan,
    DateTime.UtcNow.AddMonths(-6)
));

Delete delete = new Delete(usersTable, filter);
int rowsDeleted = manager.Delete(delete);

// SQL: DELETE FROM users
//      WHERE status = 'inactive' AND last_login < '2024-07-07'

Delete using criterion shorthand:

// Delete single user by ID
Criterion<int> criterion = new Criterion<int>(
    usersTable["id"],
    ConditionalType.Equals,
    12345
);

Delete delete = new Delete(usersTable, criterion);
int rowsDeleted = manager.Delete(delete);

// SQL: DELETE FROM users WHERE id = 12345

Delete with IN clause:

// Delete multiple users by IDs
List<int> userIds = new List<int> { 1, 2, 3, 4, 5 };

Criterion<int> criterion = new Criterion<int>(
    usersTable["id"],
    ConditionalType.In,
    userIds
);

Delete delete = new Delete(usersTable, criterion);
int rowsDeleted = manager.Delete(delete);

// SQL: DELETE FROM users WHERE id IN (1, 2, 3, 4, 5)

Delete within a transaction:

using (Manager manager = new Manager(connection))
{
    manager.LoadSchema("my_schema");
    Schema schema = manager.GetSchema("my_schema");

    manager.BeginTransaction();
    try
    {
        // Delete orders
        Delete deleteOrders = new Delete(
            schema["orders"],
            new Criterion<int>(schema["orders"]["user_id"], 12345)
        );
        manager.Delete(deleteOrders);

        // Delete user
        Delete deleteUser = new Delete(
            schema["users"],
            new Criterion<int>(schema["users"]["id"], 12345)
        );
        manager.Delete(deleteUser);

        manager.CommitTransaction();
    }
    catch
    {
        manager.RollbackTransaction();
        throw;
    }
}

Delete all rows (use with caution):

// WARNING: This deletes ALL rows from the table!
Delete delete = new Delete(usersTable);
int rowsDeleted = manager.Delete(delete);

// SQL: DELETE FROM users

Remarks

Delete operations remove rows from a table based on optional WHERE clause criteria. Always use a WHERE clause unless you intentionally want to delete all rows.

DELETE statements are executed using Engine.Manager.Delete(Delete). The number of affected rows is returned by the Manager.

WARNING: DELETE without a WHERE clause removes ALL rows from the table. Always double-check your WHERE conditions before executing.

Constructors

Delete(Table): Creates a new DELETE statement for the specified table without a WHERE clause.

Delete(Table, IEnumerable<IFilterItem>): Creates a new DELETE statement with multiple filter items.

Delete(Table, IFilterItem): Creates a new DELETE statement with a single filter item.

Delete(Table, Filter): Creates a new DELETE statement with a WHERE clause filter.

Properties

HasWhereClause: Gets whether this DELETE statement has a WHERE clause.

Table: Gets the table that rows will be deleted from.

WhereClause: Gets the WHERE clause filter that specifies which rows to delete.

Methods