Struct Function 

pub struct Function { /* private fields */ }

A MySQL function call, with every decoration the grammar hangs off one.

From 14.19 Aggregate Functions and 14.20 Window Functions:

name([DISTINCT] expr [, expr] ... [ORDER BY …])
GROUP_CONCAT([DISTINCT] expr [, expr] ... [ORDER BY …] [SEPARATOR str_val])
name(…) OVER (window_spec) | name(…) OVER window_name

MySQL has no FILTER (WHERE …) and no WITHIN GROUP. Both are on PostgreSQL’s function builder and neither is here.

Expr::Func carries only what all three dialects share, so everything above lives here and reaches core through Expr::Custom.

use keelson_mysql::{f, quote, window};

// AVG(`views`) OVER (PARTITION BY `user_id`)
let e = f("AVG", quote("views")).over(window::partition_by(quote("user_id")));

Implementations

impl Function

pub fn new( name: impl Into<Cow<'static, str>>, args: impl IntoExprList, ) -> Function

A call to name with args.

pub fn distinct(self) -> Function

DISTINCT, for an aggregate that should see each distinct input once.

pub fn order_by(self, order: impl IntoExpr) -> Function

Add a sort key to the aggregate’s own ORDER BY, rendered inside the argument list: GROUP_CONCAT(x ORDER BY y).

pub fn separator(self, separator: impl Into<Cow<'static, str>>) -> Function

SEPARATOR 'str', which only GROUP_CONCAT takes.

Written as a single-quoted literal with nothing escaped, exactly like s: this is for a separator the program itself chose.

pub fn over(self, mods: impl Mod<Window>) -> Expr

Attach OVER (…), built from window mods — mysql::window::* and mysql::frame::*.

Ends the builder, because OVER is the last thing in the grammar and nothing may follow it. over(()) gives the legal OVER (), which means the whole partition.

pub fn over_name(self, name: impl Into<Cow<'static, str>>) -> Expr

Attach OVER \w`— a reference to a window in the statement'sWINDOW` clause.

Unparenthesised, which is what makes it a reference rather than a copy.

pub fn as_(self, alias: impl Into<Cow<'static, str>>) -> Expr

f(…) AS \alias`` — the select-list alias.

Ends the builder for the same reason Chain::as_ does: an alias is not an operand.

Trait Implementations

impl Clone for Function

fn clone(&self) -> Function

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Function

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Function

fn default() -> Function

Returns the “default value” for a type.

impl Expression for Function

fn write_sql(&self, w: &mut SqlWriter<'_>)

Append this fragment to w.

impl HasOrderBy for Function

fn order_by_mut(&mut self) -> &mut OrderBy

The ORDER BY clause to modify.

impl IntoExpr for Function

fn into_expr(self) -> Expr

Perform the conversion.

impl IntoExprList for Function

fn into_expr_list(self) -> Vec<Expr>

Perform the conversion.