Trait Dialect

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pub trait Dialect: Send + Sync {
Show 19 methods    // Required methods
    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> { ... }
}

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 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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fn build_create_table(&self, table: &str, columns: &[ColumnDef]) -> String

生成 CREATE TABLE 语句

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fn build_alter_table(&self, table: &str, changes: &[TableChange]) -> String

生成 ALTER TABLE 语句

Provided Methods§

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fn quote_checked(&self, identifier: &str) -> Result<String, DbError>

L-4 修复：带校验的引用标识符

与 quote() 不同，此方法会先校验标识符：

非空
长度 ≤ MAX_IDENTIFIER_LEN (63 chars)
不含 SQL 元字符（引号、分号、空格、注释等）

校验失败时返回 DbError::InvalidInput。

建议在调用方不可信的场景（如用户输入的表名/列名）使用此方法替代 quote()。

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fn build_drop_table(&self, table: &str, if_exists: bool) -> String

生成 DROP TABLE 语句

默认实现生成标准 DROP TABLE [IF EXISTS] <table> 语法。不支持 IF EXISTS 的方言（如 DB2）应覆盖此方法。

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fn build_upsert_on_conflict( &self, conflict_columns: &[&str], update_columns: &[&str], all_columns: &[String], ) -> Option<String>

P2-6：生成批量 upsert 的冲突处理子句（ON CONFLICT / ON DUPLICATE KEY UPDATE）

参数（均为原始列名，由各方言自行 quote）：

conflict_columns: 冲突检测列（唯一键/主键），用于 ON CONFLICT (cols) 或 ON DUPLICATE KEY
update_columns: 冲突时需要更新的列；空切片表示更新所有 all_columns 中非冲突列
all_columns: 本次 INSERT 的全部列名（原始未 quote），用于确定“更新所有非冲突列“的范围

返回 None 表示该方言不支持 upsert（如 ClickHouse、Db2）。返回 Some(clause) 表示完整的冲突处理子句（不含前导空格），如：

MySQL: ON DUPLICATE KEY UPDATE \c1`=VALUES(`c1`), `c2`=VALUES(`c2`)`
PG/SQLite: ON CONFLICT ("c1") DO UPDATE SET "c2"=EXCLUDED."c2"

L3 实现深度：返回的子句使用参数化占位符（VALUES(col) 或 EXCLUDED.col），不拼接用户值，杜绝 SQL 注入。

Trait Implementations§

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impl Display for dyn Dialect

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

Formats the value using the given formatter. Read more

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§

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Dialect

Trait Dialect Copy item path

Required Methods§

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>

Trait Implementations§

impl Display for dyn Dialect

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

Dyn Compatibility§

Implementors§

impl Dialect for ClickHouseDialect

impl Dialect for DamengDialect

impl Dialect for Db2Dialect

impl Dialect for GBaseDialect

impl Dialect for GaussDbDialect

impl Dialect for KingbaseDialect

impl Dialect for MariaDbDialect

impl Dialect for MySqlDialect

impl Dialect for OracleDialect

impl Dialect for PolarDbDialect

impl Dialect for PostgreSqlDialect

impl Dialect for SqlServerDialect

impl Dialect for SqliteDialect

impl Dialect for SybaseDialect

impl Dialect for TiDbDialect

Trait Dialect