Struct diesel::query_builder::UpdateStatement

source · [−]
pub struct UpdateStatement<T, U, V = SetNotCalled, Ret = NoReturningClause> { /* private fields */ }
Expand description

Represents a complete UPDATE statement.

See update for usage examples, or the update guide for a more exhaustive set of examples.

Implementations

Provides the SET clause of the UPDATE statement.

See update for usage examples, or the update guide for a more exhaustive set of examples.

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 update(table.filter(x)) and update(table).filter(x).

Example
let updated_rows = diesel::update(users)
    .set(name.eq("Jim"))
    .filter(name.eq("Sean"))
    .execute(&connection);
assert_eq!(Ok(1), updated_rows);

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

assert_eq!(Ok(expected_names), names);

Boxes the WHERE clause of this update 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::update(users)
    .set(name.eq("Jerk"))
    .into_boxed();

if !params["tess_has_been_a_jerk"] {
    query = query.filter(name.ne("Tess"));
}

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

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

assert_eq!(expected_names, names);

Specify what expression is returned after execution of the update.

Examples
Updating a single record:
let updated_name = diesel::update(users.filter(id.eq(1)))
    .set(name.eq("Dean"))
    .returning(name)
    .get_result(&connection);
assert_eq!(Ok("Dean".to_string()), updated_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 SQL type that this query represents. Read more

Walk over this QueryFragment for all passes. Read more

Converts this QueryFragment to its SQL representation. Read more

Serializes all bind parameters in this query. Read more

Is this query safe to store in the prepared statement cache? 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 command, returning the number of rows affected. Read more

Executes the given query, returning a Vec 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

Attempts to load a single record. 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

🔬 This is a nightly-only experimental API. (toowned_clone_into)

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.