Create a table

You can execute the CREATE TABLE statement to create a table. This topic describes how to create a non-partitioned table.

Prerequisites

The current user has the user-level or database-level CREATE privilege.

Create a table

Syntax

CREATE TABLE [IF NOT EXISTS] table_name
      (table_definition_list) [table_option_list] [partition_option] [AS] select;

CREATE TABLE [IF NOT EXISTS] table_name
      LIKE table_name;

table_definition_list:
    table_definition [, table_definition ...]

table_definition:
      column_definition
    | [CONSTRAINT [constraint_name]] PRIMARY KEY index_desc
    | [CONSTRAINT [constraint_name]] UNIQUE {INDEX | KEY}
            [index_name] index_desc
    | [CONSTRAINT [constraint_name]] FOREIGN KEY
            [index_name] index_desc
            REFERENCES reference_definition
            [match_action][opt_reference_option_list]
    | {INDEX | KEY} [index_name] index_desc

column_definition_list:
    column_definition [, column_definition ...]

column_definition:
     column_name data_type
         [DEFAULT const_value] [AUTO_INCREMENT]
         [NULL | NOT NULL] [[PRIMARY] KEY] [UNIQUE [KEY]] comment
   | column_name data_type
         [GENERATED ALWAYS] AS (expr) [VIRTUAL | STORED]
         [opt_generated_column_attribute]

index_desc:
   (column_desc_list) [index_type] [index_option_list]

match_action:
   MATCH {SIMPLE | FULL | PARTIAL}

opt_reference_option_list:
   reference_option [,reference_option ...]

reference_option:
   ON {DELETE | UPDATE} {RESTRICT | CASCADE | SET NULL | NO ACTION | SET DEFAULT}

column_desc_list:
    column_desc [, column_desc ...]

column_desc:
     column_name [(length)] [ASC | DESC]

index_type:
    USING BTREE

index_option_list:
    index_option [ index_option ...]

index_option:
      [GLOBAL | LOCAL]
    | block_size
    | compression
    | STORING(column_name_list)
    | comment

table_option_list:
    table_option [ table_option ...]

table_option:
      [DEFAULT] {CHARSET | CHARACTER SET} [=] charset_name
    | [DEFAULT] COLLATE [=] collation_name
    | primary_zone
    | replica_num
    | table_tablegroup
    | block_size
    | compression
    | AUTO_INCREMENT [=] INT_VALUE
    | comment
    | DUPLICATE_SCOPE [=] "none|zone|region|cluster"
    | LOCALITY [=] "locality description"
    | ROW_FORMAT [=] REDUNDANT|COMPACT|DYNAMIC|COMPRESSED|DEFAULT
    | PCTFREE [=] num
    | parallel_clause

parallel_clause:
    {NOPARALLEL | PARALLEL integer}

partition_option:
      PARTITION BY HASH(expression)
      [subpartition_option] PARTITIONS partition_count
    | PARTITION BY KEY([column_name_list])
      [subpartition_option] PARTITIONS partition_count
    | PARTITION BY RANGE {(expression) | COLUMNS (column_name_list)}
      [subpartition_option] (range_partition_list)
    | PARTITION BY LIST {(expression) | COLUMNS (column_name_list)}
      [subpartition_option] PARTITIONS partition_count

subpartition_option:
      SUBPARTITION BY HASH(expression)
      SUBPARTITIONS subpartition_count
    | SUBPARTITION BY KEY(column_name_list)
      SUBPARTITIONS subpartition_count
    | SUBPARTITION BY RANGE {(expression) | COLUMNS (column_name_list)}
      (range_subpartition_list)
    | SUBPARTITION BY LIST(expression)

range_partition_list:
    range_partition [, range_partition ...]

range_partition:
    PARTITION partition_name
    VALUES LESS THAN {(expression_list) | MAXVALUE}

range_subpartition_list:
    range_subpartition [, range_subpartition ...]

range_subpartition:
    SUBPARTITION subpartition_name
    VALUES LESS THAN {(expression_list) | MAXVALUE}

expression_list:
    expression [, expression ...]

column_name_list:
    column_name [, column_name ...]

partition_name_list:
    partition_name [, partition_name ...]

partition_count | subpartition_count:
    INT_VALUE

Parameters

Create a non-partitioned table

A non-partitioned table is a table that has only one partition.

Examples:

Example 1: Create a table named student.

CREATE TABLE student(
  id int,
  name varchar(18),
  sex char(1),
  age int,
  address varchar(200),
  email varchar(100),
  date date,
  PRIMARY KEY (id)
);

Example 2: Create a table named staff.

CREATE TABLE staff(
  id int not null auto_increment,
  name varchar(18),
  sex char(1) default '0' check(
    sex = '0'
    or sex = '1'
  ),
  age int not null,
  address varchar(200),
  email varchar(100) unique,
  date date,
  wages number(7, 3),
  Entry_time TIMESTAMP(6),
  PRIMARY KEY (id),
  index idx (date)
);

In the preceding examples, two tables are created. Some constraints, including the primary and foreign keys, are defined on different columns.

Select the correct data types for columns when creating a table. For information about data types, see SQL Reference.

Note

• To ensure performance and facilitate maintenance, we recommend that you specify a primary key or a unique key when you create a table. If no column can be used as the primary key, the system generates an auto-increment column as the hidden primary key column after table creation.
• You cannot add a primary key to a table by using the ALTER TABLE statement. Therefore, you must specify the primary key when you create a table.

Create a table by copying the data in an existing table

Copy table data

You can execute the CREATE TABLE AS SELECT statement to copy data from a table. The constraints, indexes, default values, and partitions are lost when you copy the data.

Examples

Copy the data in the staff table to the staff_copy table. Statement:

CREATE TABLE staff_copy AS SELECT * FROM staff;

• Comparison of table data

  • Data in the staff table:

    obclient> select * from staff;
    +----+--------+------+-----+-------------------+----------------------+------------+---------+----------------------------+
    | id | name   | sex  | age | address           | email                | date       | wages   | Entry_time                 |
    +----+--------+------+-----+-------------------+----------------------+------------+---------+----------------------------+
    |  1 | Zhang San   | 0    |  15 | XX Community in Hangzhou      | 1********@QQ.com     | 2022-02-22 | 100.000 | 2022-02-25 23:59:59.999990 |
    |  2 | Li Si   | 1    |  15 | XX Community in Beijing      | 2********@163.com    | 2022-02-28 | 100.000 | 2022-02-27 23:59:59.999990 |
    |  3 | Wang Wu   | 1    |  15 | XX Community in Shanghai      | 3********@shouhu.com | 2022-02-28 | 100.000 | 2022-04-28 23:59:59.999990 |
    +----+--------+------+-----+-------------------+----------------------+------------+---------+----------------------------+
    3 rows in set
    

  • Data in the staff_copy table:

    obclient> select * from staff_copy;
    +----+--------+------+-----+-------------------+----------------------+------------+---------+----------------------------+
    | id | name   | sex  | age | address           | email                | date       | wages   | Entry_time                 |
    +----+--------+------+-----+-------------------+----------------------+------------+---------+----------------------------+
    |  1 | Zhang San   | 0    |  15 | XX Community in Hangzhou      | 1********@QQ.com     | 2022-02-22 | 100.000 | 2022-02-25 23:59:59.999990 |
    |  2 | Li Si   | 1    |  15 | XX Community in Beijing      | 2********@163.com    | 2022-02-28 | 100.000 | 2022-02-27 23:59:59.999990 |
    |  3 | Wang Wu   | 1    |  15 | XX Community in Shanghai      | 3********@shouhu.com | 2022-02-28 | 100.000 | 2022-04-28 23:59:59.999990 |
    +----+--------+------+-----+-------------------+----------------------+------------+---------+----------------------------+
    3 rows in set
    

• Comparison of table structures

  • Structure of the staff table:

    obclient> desc staff;
    +------------+--------------+------+-----+---------+----------------+
    | Field      | Type         | Null | Key | Default | Extra          |
    +------------+--------------+------+-----+---------+----------------+
    | id         | int(11)      | NO   | PRI | NULL    | auto_increment |
    | name       | varchar(18)  | YES  |     | NULL    |                |
    | sex        | char(1)      | YES  |     | 0       |                |
    | age        | int(11)      | NO   |     | NULL    |                |
    | address    | varchar(200) | YES  |     | NULL    |                |
    | email      | varchar(100) | YES  | UNI | NULL    |                |
    | date       | date         | YES  | MUL | NULL    |                |
    | wages      | decimal(7,3) | YES  |     | NULL    |                |
    | Entry_time | timestamp(6) | YES  |     | NULL    |                |
    +------------+--------------+------+-----+---------+----------------+
    9 rows in set
    

  • Structure of the staff_copy table:

    obclient> desc staff_copy;
    +------------+--------------+------+-----+---------+-------+
    | Field      | Type         | Null | Key | Default | Extra |
    +------------+--------------+------+-----+---------+-------+
    | id         | int(11)      | NO   |     | NULL    |       |
    | name       | varchar(18)  | YES  |     | NULL    |       |
    | sex        | char(1)      | YES  |     | NULL    |       |
    | age        | int(11)      | NO   |     | NULL    |       |
    | address    | varchar(200) | YES  |     | NULL    |       |
    | email      | varchar(100) | YES  |     | NULL    |       |
    | date       | date         | YES  |     | NULL    |       |
    | wages      | decimal(7,3) | YES  |     | NULL    |       |
    | Entry_time | timestamp(6) | YES  |     | NULL    |       |
    +------------+--------------+------+-----+---------+-------+
    9 rows in set
    

Note

The comparison results show that data in the destination staff_copy table is the same as that in the source staff table, but the constraints, indexes, and default values are missing in the structure of the staff_copy table.

Copy the table structure

You can also execute the CREATE TABLE LIKE statement to copy the structure but not the data of a table. Example:

Copy the structure of the staff table to the staff_like table.

Sample statement:

CREATE TABLE staff_like like staff;

• Comparison of table structures

  • Structure of the staff table:

    obclient> desc staff;
    +------------+--------------+------+-----+---------+----------------+
    | Field      | Type         | Null | Key | Default | Extra          |
    +------------+--------------+------+-----+---------+----------------+
    | id         | int(11)      | NO   | PRI | NULL    | auto_increment |
    | name       | varchar(18)  | YES  |     | NULL    |                |
    | sex        | char(1)      | YES  |     | 0       |                |
    | age        | int(11)      | NO   |     | NULL    |                |
    | address    | varchar(200) | YES  |     | NULL    |                |
    | email      | varchar(100) | YES  | UNI | NULL    |                |
    | date       | date         | YES  | MUL | NULL    |                |
    | wages      | decimal(7,3) | YES  |     | NULL    |                |
    | Entry_time | timestamp(6) | YES  |     | NULL    |                |
    +------------+--------------+------+-----+---------+----------------+
    9 rows in set
    

  • Structure of the staff_like table:

    obclient> desc staff_like;
    +------------+--------------+------+-----+---------+----------------+
    | Field      | Type         | Null | Key | Default | Extra          |
    +------------+--------------+------+-----+---------+----------------+
    | id         | int(11)      | NO   | PRI | NULL    | auto_increment |
    | name       | varchar(18)  | YES  |     | NULL    |                |
    | sex        | char(1)      | YES  |     | 0       |                |
    | age        | int(11)      | NO   |     | NULL    |                |
    | address    | varchar(200) | YES  |     | NULL    |                |
    | email      | varchar(100) | YES  | UNI | NULL    |                |
    | date       | date         | YES  | MUL | NULL    |                |
    | wages      | decimal(7,3) | YES  |     | NULL    |                |
    | Entry_time | timestamp(6) | YES  |     | NULL    |                |
    +------------+--------------+------+-----+---------+----------------+
    9 rows in set
    

• Comparison of the number of rows

  • Number of rows in the staff table:

    obclient> select count(*) from staff;
    +----------+
    | count(*) |
    +----------+
    |        3 |
    +----------+
    1 row in set
    

  • Number of rows in the staff_like table:

    obclient> select count(*) from staff_like;
    +----------+
    | count(*) |
    +----------+
    |        0 |
    +----------+
    1 row in set (0.01 sec)
    

Create a replica table

Table replication is an advanced tuning technique in OceanBase Database.

In general, OceanBase uses a three-replica architecture. By default, each partition of a table exists in three replicas. One of the replicas is the leader, and the others are followers. By default, the leader provides write and read services.

You can create a replica table on every server in the tenant. You can have only one leader and two or more followers in the tenant. Full data synchronization is implemented to maintain strong consistency between the leader and followers. This allows your application to execute specific SQL JOIN queries on the same server for better performance.

To create a replica table, add a DUPLICATE_SCOPE clause to the CREATE TABLE statement.

Example:

Create a table named staff_DC that uses the zstd compression algorithm. Enable the encoding storage format, and set the reserved space for macroblocks to 0, the microblock size to 16384, the attribute of the table to cluster-level replica table, and the locality to F@zone1.

CREATE TABLE staff_DC(
  id int not null auto_increment,
  name varchar(18),
  sex char(1) default '0' check(
    sex = '0'
    or sex = '1'
  ),
  age int not null,
  address varchar(200),
  email varchar(100) unique,
  date date,
  wages number(7, 3),
  Entry_time TIMESTAMP(6),
  PRIMARY KEY (id)
) COMPRESSION 'zstd_1.0' FORM ROW_FORMAT DYNAMIC PCTFREE 0 BLOCK_SIZE = 16384 DUPLICATE_SCOPE = 'cluster' locality = 'F@zone1';