General syntax

This topic describes the general syntax of SQL statements, including the syntax of constants, character sets, data types, SQL properties, distributed properties, and storage properties.

Constants

• INT_VALUE: matches integer constants such as 123.

• DECIMAL_VALUE: matches fixed-point constants such as 123.456.

• STR_VALUE: matches string constants such as abc.

• NULL: matches NULL constants.

• STORAGE_SIZE: matches storage size constants. The default unit of integer values is bytes, and the unit of string values can be set to M or G. For example, the size can be 1024 or '500M'.

const_value:
      INT_VALUE
    | DECIMAL_VALUE
    | STR_VALUE
    | NULL
    | STORAGE_SIZE

STORAGE_SIZE:
      INT_VALUE
    | 'INT_VALUE[M|G]'

Character sets

charset:
      default_charset
    | column_charset

default_charset:
    [DEFAULT] {CHARSET | CHARACTER SET} [=] {UTF8 | UTF8MB4 | BINARY}

column_charset:
    {CHARSET | CHARACTER SET} {UTF8 | UTF8MB4 | BINARY}

Collations

collate:
      default_collate
    | column_collate

default_collate:
    [DEFAULT] COLLATE [=] {UTF8MB4_GENERAL_CI | UTF8MB4_BIN | BINARY}

column_collate:
    COLLATE {UTF8MB4_GENERAL_CI | UTF8MB4_BIN | BINARY}

Data types

data_type:
      TINYINT[(precision)] [UNSIGNED] [ZEROFILL]
    | SMALLINT[(precision)] [UNSIGNED] [ZEROFILL]
    | MEDIUMINT[(precision)] [UNSIGNED] [ZEROFILL]
    | INT[(precision)] [UNSIGNED] [ZEROFILL]
    | INTEGER[(precision)] [UNSIGNED] [ZEROFILL]
    | BIGINT[(precision)] [UNSIGNED] [ZEROFILL]
    | FLOAT[(precision, scale)] [UNSIGNED] [ZEROFILL]
    | DOUBLE[(precision, scale)] [UNSIGNED] [ZEROFILL]
    | DECIMAL[(precision [, scale])] [UNSIGNED] [ZEROFILL]
    | NUMERIC[(precision [, scale])] [UNSIGNED] [ZEROFILL]
    | DATETIME[(scale)]
    | TIMESTAMP[(scale)]
    | DATE
    | TIME[(scale)]
    | YEAR
    | VARCHAR(length) column_charset column_collate
    | VARBINARY(length)
    | CHAR[(length)] column_charset column_collate
    | BINARY[(length)]
    | TINYTEXT column_charset column_collate
    | TINYLOB
    | TEXT[(length)] column_charset column_collate
    | BLOB[(length)]
    | MEDIUMTEXT column_charset column_collate
    | MEDIUMBLOB
    | LONGTEXT column_charset column_collate
    | LONGBLOB

precision | scale | length:
    INT_VALUE

SQL properties

• Object name

  tenant_name | pool_name | unit_name | zone_name | region_name:
      STR_VALUE
  
  database_name | table_name | table_alias_name | column_name| column_alias_name  | partition_name | subpartition_name:
      STR_VALUE
  
  index_name | view_name | object_name | constraint_name | tablegroup_name:
      STR_VALUE
  
  outline_name | user_name:
      STR_VALUE
  
  table_factor:
      [[database_name].] table_name
  
  column_factor:
      [table_factor.] column_name
  

• Expression

  expression:
        const_value
      | column_factor
      | operator_expression
      | function_expression
  

• Comment

  comment:
      COMMENT 'comment_text'
  
  comment_text:
      STR_VALUE
  

Distributed properties

• PRIMARY_ZONE: specifies the leader distribution strategy for data.

  primary_zone:
  PRIMARY_ZONE [=] zone_name
  

• ZONE_LIST: specifies the resource distribution strategy for a tenant.

  zone_list:
  ZONE_LIST [=] (zone_name [, zone_name ...])
  

• REPLICA_NUM: specifies the number of replicas of data.

  replica_num:
  REPLICA_NUM [=] INT_VALUE
  

• TABLEGROUP: specifies the leader distribution strategy for multiple data replicas.

  tablegroup:
        default_tablegroup
      | table_tablegroup
  
  default_tablegroup:
      DEFAULT TABLEGROUP [=] {tablegroup_name | NULL}
  
  table_tablegroup:
      TABLEGROUP [=] {tablegroup_name | NULL}
  

Storage properties

• BLOCK_SIZE: specifies the microblock size for object storage.

  block_size:
  BLOCK_SIZE [=] INT_VALUE
  

• COMPRESSION: specifies the compression algorithm for object storage.

  compression:
  COMPRESSION [=] {NONE | LZ4_1.0 | LZ0_1.0 | SNAPPY_1.0 | ZLIB_1.0}
  

  Note

  The zlib compression algorithm of different minor versions may generate different compression results for the same data. To avoid replica restore failures during an upgrade, the zlib_1.0 compression algorithm is no longer supported starting from OceanBase Database V4.3.0.

• PCTFREE: specifies the macroblock reservation percentage for object storage.

  pctfree:
  PCTFREE [=] INT_VALUE
  

• TABLET_SIZE: specifies the minimum tablet size of a single task in a parallel compaction.

  tablet_size:
  TABLET_SIZE [=] INT_VALUE