Oracle 与LightDB alter table 语法对比（部分）

Posted 2023-02-27 紫无之紫

Oracle 与LightDB alter table 语法对比（部分）

本文对oracle（21）和lightdb（22.3）中常用的一些alter table 语法进行比较， 包括修改字段属性， 修改约束，修改表为分区表等。

1. 修改字段（包括添加删除）

1.1 修改字段属性

对常用的修改字段属性语法进行比较

功能	oracle	lightdb	mysql
修改默认值	modify column default def_val	modify column default def_val alter column set default def_val
修改为null	modify column null	modify column null alter column drop not null
修改为 not null	modify column not null	modify column not null alter column set not null
修改字段类型	modify column Typename	modify column Typename alter [COLUMN] type Typename
修改字段IDENTITY	modify GENERATED … AS IDENTITY OptParenthesizedSeqOptListmodify modify DROP IDENTITY	ALTER [COLUMN] ADD GENERATED … AS IDENTITY OptParenthesizedSeqOptList modify GENERATED … AS IDENTITY OptParenthesizedSeqOptList ALTER TABLE ALTER [COLUMN] DROP IDENTITY modify DROP IDENTITY
修改字段类型	modify Typename	ALTER_or_MODIFY opt_column ColId opt_set_data TYPE_P Typename opt_collate_clause alter_using modify Typename alter_using
新增约束	modify column inline_constraint	modify column inline_constraint
此字段在插入null 时转换为默认值	modify ColId default xxx	不支持
其他	encrypt/decrypt LOB_storage_clause alter_XMLSchema_clause modify_virtcol_properties modify_col_visibility modify_col_substitutable	不支持
rename 字段	RENAME COLUMN column_name TO new_column_name 必须有COLUMN关键字	RENAME [ COLUMN ] column_name TO new_column_name

oracle inline_constraint：

1.2. 添加字段

oracle 与lightdb 的常用的添加字段的用法相同 ，都可以通过如下方式添加字段：

ADD column_name column_type [ COLLATE collation ] [default xxx] [not null/null] [unique/primary key] [check ( expression )]

oracle 支持在一条sql 添加多个字段, lightdb 目前不支持:

add (column_def, column_def, ...)

具体各自的语法如下：

oracle语法

column_definition:

inline_constraint:

更具体的可以参考oracle官方文档¹

lightdb 语法

ADD [ COLUMN ] [ IF NOT EXISTS ] column_name data_type [ COLLATE collation ] [ column_constraint [ ... ] ]

column_constraint:
    [ CONSTRAINT constraint_name ]
     NOT NULL |
      NULL |
      CHECK ( expression ) [ NO INHERIT ] |
      DEFAULT default_expr |
      GENERATED ALWAYS AS ( generation_expr ) STORED |
      GENERATED  ALWAYS | BY DEFAULT  AS IDENTITY [ ( sequence_options ) ] |
      UNIQUE index_parameters |
      PRIMARY KEY index_parameters |
      REFERENCES reftable [ ( refcolumn ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
        [ ON DELETE referential_action ] [ ON UPDATE referential_action ] 
    [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]

更具体的可以参考lightdb官方文档²

1.3. 删除字段

oracle 与lightdb 的常用的删除字段的用法相同 ，都可以通过如下方式删除字段：

drop COLUMN column_name

oracle 支持在一条sql 添加多个字段, lightdb 目前不支持, 却oracle 删除字段如果不带COLUMN关键字，需要把字段名括起来:

drop (column_name, column_name, ...)

具体各自的语法如下：

oracle 删除字段语法

lightdb 删除字段语法

DROP [ COLUMN ] [ IF EXISTS ] column_name [ RESTRICT | CASCADE ]

2. 修改约束（包括添加删除）

下面对修改约束的基本用法进行比较， 各自的具体用法请参考具体语法

2.1. 添加约束

添加约束的常用语法也相同，支持如下：

ADD table_constraint

table_constraint:
[ CONSTRAINT constraint_name ]
 CHECK ( expression )  |
  UNIQUE ( column_name [, ... ] ) |
  PRIMARY KEY ( column_name [, ... ] ) |
  FOREIGN KEY ( column_name [, ... ] ) REFERENCES reftable [ ( refcolumn [, ... ] ) ]
 
[ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]

2.2. 删除约束

都支持如下基本用法：

DROP CONSTRAINT constraint_name [cascade]
DROP PRIMARY KEY [cascade]

oracle 还支持如下方式删除唯一索引, lightdb 暂不支持：

DROP UNIQUE(COLUMN_NAME, COLUMN_NAME, ...)

2.3. 修改约束状态

oracle 通过MODIFY关键字修改约束状态，lightdb 通过alter 关键字修改,且lightdb不支持修改通过PRIAMRY KEY/UNIQUE(COLUMN,…) 修改主键，唯一约束的状态。

2.4. rename 约束

相同， 语法如下：

RENAME CONSTRAINT constraint_name TO new_constraint_name

2.5 具体语法

oracle 修改约束语法

constraint_clauses:

out_of_line_constraint:

drop_constraint_clause:

lightdb 修改约束语法

ADD table_constraint [ NOT VALID ]
ADD table_constraint_using_index
ALTER CONSTRAINT constraint_name [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
RENAME CONSTRAINT constraint_name TO new_constraint_name
VALIDATE CONSTRAINT constraint_name

table_constraint:
    [ CONSTRAINT constraint_name ]
     CHECK ( expression ) [ NO INHERIT ] |
      UNIQUE ( column_name [, ... ] ) index_parameters |
      PRIMARY KEY ( column_name [, ... ] ) index_parameters |
      EXCLUDE [ USING index_method ] ( exclude_element WITH operator [, ... ] ) index_parameters [ WHERE ( predicate ) ] |
      FOREIGN KEY ( column_name [, ... ] ) REFERENCES reftable [ ( refcolumn [, ... ] ) ]
        [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE action ] [ ON UPDATE action ] 
    [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
    
table_constraint_using_index:
    [ CONSTRAINT constraint_name ]
     UNIQUE | PRIMARY KEY  USING INDEX index_name
    [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]

3. oracle外部表

lightdb 不支持类似oracle的外部表

4. 修改为分区表

lightdb 暂不支持

oracle 修改为分区表语法

5. 修改表属性

都支持常用的如下用法rename name 和修改collation

rename to new_name
DEFAULT COLLATION collation_name

oracle 修改表属性语法

alter_table_properties:

lightdb 修改表属性语法

RENAME TO new_name
SET SCHEMA new_schema
ALTER TABLE ALL IN TABLESPACE name [ OWNED BY role_name [, ... ] ]
    SET TABLESPACE new_tablespace [ NOWAIT ]    -- 修改表空间
ALTER TABLE [ IF EXISTS ] name
    ATTACH PARTITION partition_name  FOR VALUES partition_bound_spec | DEFAULT 
ALTER TABLE [ IF EXISTS ] name
    DETACH PARTITION partition_name
    DISABLE TRIGGER [ trigger_name | ALL | USER ]
    ENABLE TRIGGER [ trigger_name | ALL | USER ]
    ENABLE REPLICA TRIGGER trigger_name
    ENABLE ALWAYS TRIGGER trigger_name
    DISABLE RULE rewrite_rule_name
    ENABLE RULE rewrite_rule_name
    ENABLE REPLICA RULE rewrite_rule_name
    ENABLE ALWAYS RULE rewrite_rule_name
    DISABLE ROW LEVEL SECURITY
    ENABLE ROW LEVEL SECURITY
    FORCE ROW LEVEL SECURITY
    NO FORCE ROW LEVEL SECURITY
    CLUSTER ON index_name
    SET WITHOUT CLUSTER
    SET WITHOUT OIDS
    SET TABLESPACE new_tablespace
    SET  LOGGED | UNLOGGED 
    SET ( storage_parameter [= value] [, ... ] )
    RESET ( storage_parameter [, ... ] )
    INHERIT parent_table
    NO INHERIT parent_table
    OF type_name
    NOT OF
    OWNER TO  new_owner | CURRENT_USER | SESSION_USER 
    REPLICA IDENTITY  DEFAULT | USING INDEX index_name | FULL | NOTHING 

参考文档

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1. https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/ALTER-TABLE.html#GUID-552E7373-BF93-477D-9DA3-B2C9386F2877 ↩︎

2. http://www.light-pg.com/docs/lightdb/13.3-22.2/sql-altertable.html ↩︎