Trait Dialect

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pub trait Dialect: Send + Sync {
Show 24 methods    // Required methods
    fn clone_box(&self) -> Box<dyn Dialect>;
    fn db_type(&self) -> DbType;
    fn quote(&self, identifier: &str) -> String;
    fn escape_string(&self, s: &str) -> String;
    fn supports_returning(&self) -> bool;
    fn build_pagination(&self, sql: &str, page: u64, limit: u64) -> String;
    fn json_type(&self) -> &'static str;
    fn json_extract(&self, column: &str, path: &str) -> String;
    fn full_text_search(&self, columns: &[&str], keyword: &str) -> String;
    fn bool_to_int(&self, expr: &str) -> String;
    fn concat(&self, parts: &[&str]) -> String;
    fn supports_if_exists(&self) -> bool;
    fn supports_if_not_exists(&self) -> bool;
    fn auto_increment_keyword(&self) -> &'static str;
    fn last_insert_id_sql(&self) -> Option<&'static str>;
    fn build_create_table(&self, table: &str, columns: &[ColumnDef]) -> String;
    fn build_alter_table(&self, table: &str, changes: &[TableChange]) -> String;

    // Provided methods
    fn quote_checked(&self, identifier: &str) -> Result<String, DbError> { ... }
    fn build_drop_table(&self, table: &str, if_exists: bool) -> String { ... }
    fn build_upsert_on_conflict(
        &self,
        conflict_columns: &[&str],
        update_columns: &[&str],
        all_columns: &[String],
    ) -> Option<String> { ... }
    fn build_lock_clause(&self, lock_type: LockType) -> Option<String> { ... }
    fn supports_lock_for_update(&self) -> bool { ... }
    fn supports_lock_shared(&self) -> bool { ... }
    fn build_insert_or_ignore_prefix(&self, table: &str) -> String { ... }
}

Expand description

数据库方言 trait

实现者负责处理各数据库特有的 SQL 语法差异

Required Methods§

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fn clone_box(&self) -> Box<dyn Dialect>

克隆为 trait object（用于 QueryBuilder::clone_for_count）。

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fn db_type(&self) -> DbType

返回该方言对应的数据库类型

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fn quote(&self, identifier: &str) -> String

引用标识符（表名、列名等）

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fn escape_string(&self, s: &str) -> String

转义字符串字面量，确保可安全嵌入 SQL

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fn supports_returning(&self) -> bool

该方言是否支持 RETURNING 子句

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fn build_pagination(&self, sql: &str, page: u64, limit: u64) -> String

生成分页 SQL

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fn json_type(&self) -> &'static str

获取 JSON 类型的 SQL 类型名

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fn json_extract(&self, column: &str, path: &str) -> String

生成 JSON_EXTRACT 函数调用

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fn full_text_search(&self, columns: &[&str], keyword: &str) -> String

生成全文检索 SQL

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fn bool_to_int(&self, expr: &str) -> String

将布尔表达式转换为整型存储

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fn concat(&self, parts: &[&str]) -> String

生成 CONCAT 函数调用

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fn supports_if_exists(&self) -> bool

该方言是否支持 IF EXISTS

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fn supports_if_not_exists(&self) -> bool

该方言是否支持 IF NOT EXISTS

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fn auto_increment_keyword(&self) -> &'static str

获取自增列关键字

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fn last_insert_id_sql(&self) -> Option<&'static str>

获取最近插入 ID 的 SQL（独立可执行语句）

返回 None 表示该方言不支持以独立 SQL 获取最后插入 ID（如 Oracle 只能通过在 INSERT 语句末尾附加 RETURNING ... INTO :bind 子句的方式获取，无法独立执行）。调用方在拿到 None 时必须改用 supports_returning() + 在 INSERT 后追加 RETURNING。

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