command

command#

Execute a single SQL INSERT, UPDATE, or DELETE statement.

Rust API#

// sync_api
pub fn mudu_command(
    oid: OID,
    sql: &dyn SQLStmt,
    params: &dyn SQLParams,
) -> RS<u64> {
    /* ... */
}

// async_api
pub async fn mudu_command(
    oid: OID,
    sql: &dyn SQLStmt,
    params: &dyn SQLParams,
) -> RS<u64> {
    /* ... */
}

Conceptual signature#

command(sql: string, params?: [Value]) -> affected_rows: u64

Parameters#

  • sql — a single SQL statement using ? as parameter placeholders.

  • params — values bound to the placeholders.

Return value#

  • u64 — the number of rows affected by the statement.

Errors#

  • SyntaxError: the SQL statement is invalid.

  • ConstraintViolation: schema or uniqueness violation.

  • NotFound: update/delete on a non-existing key, depending on op mode.

  • SerializationError / Conflict: transaction conflict requiring retry.

Transaction semantics#

  • The command participates in the current session transaction.

  • Outside a transaction, behavior is host-defined (autocommit or reject).

Example#

let affected = mudu_command(
    oid,
    sql_stmt!("UPDATE accounts SET balance = balance - ? WHERE id = ?"),
    sql_params!(&(amount, from_id)),
)?;
assert_eq!(affected, 1);

Notes#

  • Use command for DML statements. For SELECT, use query.

  • For multiple statements in one call, consider batch.

  • Prefer typed syscall primitives (read, write) for structured access when available.