pub struct DeleteStatement<T: QuerySource, U, Ret = NoReturningClause> { /* private fields */ }
Expand description

Represents a SQL DELETE statement.

The type parameters on this struct represent:

  • T: The table we are deleting from.
  • U: The WHERE clause of this query. The exact types used to represent this are private, and you should not make any assumptions about them.
  • Ret: The RETURNING clause of this query. The exact types used to represent this are private. You can safely rely on the default type representing the lack of a RETURNING clause.

Implementations§

Adds the given predicate to the WHERE clause of the statement being constructed.

If there is already a WHERE clause, the predicate will be appended with AND. There is no difference in behavior between delete(table.filter(x)) and delete(table).filter(x).

Example
let deleted_rows = diesel::delete(users)
    .filter(name.eq("Sean"))
    .execute(connection);
assert_eq!(Ok(1), deleted_rows);

let expected_names = vec!["Tess".to_string()];
let names = users.select(name).load(connection);

assert_eq!(Ok(expected_names), names);

Adds to the WHERE clause of a query using OR

If there is already a WHERE clause, the result will be (old OR new). Calling foo.filter(bar).or_filter(baz) is identical to foo.filter(bar.or(baz)). However, the second form is much harder to do dynamically.

Example
let deleted_rows = diesel::delete(users)
    .filter(name.eq("Sean"))
    .or_filter(name.eq("Tess"))
    .execute(connection);
assert_eq!(Ok(2), deleted_rows);

let num_users = users.count().first(connection);

assert_eq!(Ok(0), num_users);

Boxes the WHERE clause of this delete statement.

This is useful for cases where you want to conditionally modify a query, but need the type to remain the same. The backend must be specified as part of this. It is not possible to box a query and have it be useable on multiple backends.

A boxed query will incur a minor performance penalty, as the query builder can no longer be inlined by the compiler. For most applications this cost will be minimal.

Example
let mut query = diesel::delete(users)
    .into_boxed();

if params["sean_has_been_a_jerk"] {
    query = query.filter(name.eq("Sean"));
}

let deleted_rows = query.execute(connection)?;
assert_eq!(1, deleted_rows);

let expected_names = vec!["Tess"];
let names = users.select(name).load::<String>(connection)?;

assert_eq!(expected_names, names);

Specify what expression is returned after execution of the delete.

Examples
Deleting a record:
let deleted_name = diesel::delete(users.filter(name.eq("Sean")))
    .returning(name)
    .get_result(connection);
assert_eq!(Ok("Sean".to_string()), deleted_name);

Trait Implementations§

The SQL type of Self::Query
What kind of query does this type represent?
Converts a type which semantically represents a SQL query into the actual query being executed. See the trait level docs for more. Read more
The return type of internal_into_boxed
See the trait documentation.
Returns a copy of the value. Read more
Performs copy-assignment from source. Read more
Formats the value using the given formatter. Read more
The type returned by .filter.
See the trait documentation.
The type returned by .filter.
See the trait documentation.
The SQL type that this query represents. Read more
A type which uniquely represents Self in a SQL query. Read more
Can the SQL generated by Self be uniquely identified by its type? Read more
Returns the type id of Self::QueryId if Self::HAS_STATIC_QUERY_ID. Returns None otherwise. Read more
Executes the given query, returning a Vec with the returned rows. Read more
Executes the given query, returning an Iterator with the returned rows. Read more
Runs the command, and returns the affected row. Read more
Runs the command, returning an Vec with the affected rows. Read more

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
The SQL type of Self::Query
What kind of query does this type represent?
Converts a type which semantically represents a SQL query into the actual query being executed. See the trait level docs for more. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
Execute this command

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

Convert self to an expression for Diesel’s query builder. Read more
Convert &self to an expression for Diesel’s query builder. Read more
The resulting type after obtaining ownership.
Creates owned data from borrowed data, usually by cloning. Read more
Uses borrowed data to replace owned data, usually by cloning. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.