MakeDeleter()

template<EntityValueType ENTITY>

constexpr auto sqt::DataContext< ENTITY >::MakeDeleter ( )

staticconstexprnoexcept

Creates a deleter for deleting rows from the database table.

Returns

A new deleter instance.

The returned deleter corresponds to a DELETE SQL statement without any conditions, so it will deleter all rows from the table. To control which rows to delete, use the Where() method of the deleter to create a new deleter with conditions. The following code demonstrates how to use the deleter:

// The entity type, assuming its table type has been defined and registered, and its
// columns' names are defined as the same as the entity's field names.
struct MyEntity {
    int id{};
    std::string name;
};
 
// Create the deleter with a condition.
constexpr auto deleter = sqt::DataContext<MyEntity>::MakeDeleter().Where(
    sqt::Table<MyEntity>.id == 1
);
 
// Create a data context, assuming the shared_db is an opened database instance.
sqt::DataContext<MyEntity> data_context{ shared_db };
 
// Prepare the deleter to create a corresponding executor.
auto executor = data_context.Prepare(deleter);
 
// Execute the statement.
executor.Execute();

For easier-to-use methods, use the following methods from the easy style interface:

• Delete() for deleting a row by the specified primary key value.
• DeleteAll() for deleting all rows in the table.

See also

sqt::DataContext<>::Delete()

sqt::DataContext<>::DeleteAll()