Struct MergeQuery 

pub struct MergeQuery {
    pub with: With,
    pub target: TableRef,
    pub source: TableRef,
    pub on: Vec<Expr>,
    pub whens: Vec<MergeWhen>,
    pub returning: Returning,
}

A PostgreSQL MERGE (PostgreSQL 15+).

From https://www.postgresql.org/docs/17/sql-merge.html:

[ WITH with_query [, ...] ]
MERGE INTO [ ONLY ] target_table_name [ * ] [ [ AS ] target_alias ]
    USING data_source ON join_condition
    when_clause [...]
    [ RETURNING … ]

when_clause:
    WHEN MATCHED [ AND condition ] THEN { merge_update | merge_delete | DO NOTHING }
  | WHEN NOT MATCHED BY SOURCE [ AND condition ] THEN
        { merge_update | merge_delete | DO NOTHING }
  | WHEN NOT MATCHED [ BY TARGET ] [ AND condition ] THEN
        { merge_insert | DO NOTHING }

Three parts of the production are newer than 15 and are marked where the API produces them: WHEN NOT MATCHED BY SOURCE, the explicit BY TARGET spelling, and RETURNING are all PostgreSQL 17+.

The target lives in HasTargetTable — like an UPDATE’s table — and the USING source in HasTableRef, like a DELETE’s USING item, which is what lets one TableChain serve both slots. The source also carries HasJoins: gram.y’s MergeStmt reads USING table_ref ON a_expr, and a table_ref may be a joined_table, so a joined source is grammatical. The target is a relation_expr_opt_alias, which admits no joins — the same split an UPDATE has.

Which actions a WHEN clause may take depends on which WHEN it is, and that is enforced by the chain types in crate::merge rather than re-checked here: a MergeWhen holds whatever it was built with.

Fields

with: With

WITH …. MERGE takes a plain WITH; PostgreSQL rejects WITH RECURSIVE on it at analysis time, which is why crate::merge does not re-export recursive.

target: TableRef

The target: MERGE INTO [ ONLY ] table [ * ] [ AS alias ].

source: TableRef

The data source: a table or a parenthesised query, with an alias.

on: Vec<Expr>

The ON join condition. Several entries are AND-joined, as in a join’s ON.

whens: Vec<MergeWhen>

The WHEN clauses, applied in order — the grammar requires at least one.

returning: Returning

RETURNING … (PostgreSQL 17+).

Implementations

impl MergeQuery

pub fn new() -> MergeQuery

A MERGE with nothing set yet.

pub fn apply(&mut self, mods: impl Mod<MergeQuery>)

Apply more mods to an existing query.

Trait Implementations

impl Clone for MergeQuery

fn clone(&self) -> MergeQuery

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MergeQuery

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

Formats the value using the given formatter.

impl Default for MergeQuery

fn default() -> MergeQuery

Returns the “default value” for a type.

impl Expression for MergeQuery

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

Append this fragment to w.

impl HasJoins for MergeQuery

fn joins_mut(&mut self) -> &mut Vec<Join>

The join list to modify.

impl HasReturning for MergeQuery

fn returning_mut(&mut self) -> &mut Returning

The RETURNING clause to modify.

impl HasTableRef for MergeQuery

fn table_ref_mut(&mut self) -> &mut TableRef

The table reference to modify.

impl HasTargetTable for MergeQuery

fn target_table_mut(&mut self) -> &mut TableRef

The target table to modify.

impl HasWith for MergeQuery

fn with_mut(&mut self) -> &mut With

The WITH clause to modify.

impl IntoExpr for MergeQuery

fn into_expr(self) -> Expr

Perform the conversion.

impl IntoExprList for MergeQuery

fn into_expr_list(self) -> Vec<Expr>

Perform the conversion.

impl Mod<MergeQuery> for MergeInsertChain

fn apply(self, q: &mut MergeQuery)

Apply this modification to q.

impl Mod<MergeQuery> for MergeWhenMod

fn apply(self, q: &mut MergeQuery)

Apply this modification to q.

impl Query for MergeQuery

fn query_type(&self) -> QueryType

Which statement this renders.

fn dialect(&self) -> &dyn Dialect

The dialect this query renders itself in.

fn build(&self) -> Result<(String, Vec<Value>), Error>

Render to SQL and arguments, numbering placeholders from 1.

fn build_from(&self, start: usize) -> Result<(String, Vec<Value>), Error>

build with a different first placeholder position, for splicing into a statement that already has arguments — bob’s BuildN.

impl<H, L, M> QueryExtensions<H, L, M> for MergeQuery

fn hooks(&self) -> &[Hook]

Hooks to run before this query executes.

fn loaders(&self) -> &[Loader]

Loaders to run after this query executes, for eagerly loaded relations.

fn mapper_mods(&self) -> &[MapperMod]

Adjustments to the row mapper, for relations loaded in the same query.