Create a table

Step 1: Specify the basic information

1. Log on to the ODC console and click the name of the desired connection to go to the corresponding connection management page. You can click Table in the left-side navigation pane to view tables. To create a table, click the plus sign (+) in the upper-right corner of the table list or click Create in the top navigation bar.

2. In the Basic Info section, set the Table Name and Description parameters.

   

   Note

   • In MySQL mode, you also need to set the Default Character Set and Default Collation parameters.
   • After you specify the basic information and go to the "Set columns" step, the basic information is submitted.
   • Only OceanBase V4.3.0 and later versions support configuring columnar storage.

Step 2: Set columns

The following figure and table show the information that you need to specify when you add a column.

The following table describes operations that you can perform on the column setting page.

Step 3: Set indexes

If a table contains a large amount of data, you can use indexes to accelerate data queries. An index is a data structure that pre-sorts the values of one or more columns in a table. By using indexes, you can directly locate records that meet the conditions.

The following figure and table show the information that you need to specify when you set an index.

The index setting page provides the following icons.

Step 4: Set constraints

Constraints are used to specify data rules for a table. A data operation that violates the constraints is terminated.

ODC supports the following four types of table constraints:

• PRIMARY KEY constraint: defines a primary key to uniquely identify each row of data in the table. A PRIMARY KEY constraint can be a field or a group of fields. You can set only one PRIMARY KEY constraint for a table, and you cannot modify the PRIMARY KEY constraint after you configure the constraint.

• UNIQUE constraint: ensures that the data in a field or a group of fields is unique in the table. You can set multiple UNIQUE constraints in one table.

• FOREIGN KEY constraint: associates one or more columns in two tables. A FOREIGN KEY constraint is used to maintain the data consistency and integrity between associated tables. After you complete the setting of FOREIGN KEY constraints, you cannot create new constraints or modify existing constraints.

• CHECK constraints: checks the data in the database based on the configured check rules when you edit the data. Data modification is allowed only after the check is passed.

OceanBase Database supports different constraints in MySQL and Oracle modes, and different constraints require different information. Therefore, you need to specify the required information based on the constraint you selected and the requirements on the page.

The constraint setting page provides the following icons.

Step 5: Set partitioning rules

You can partition a table that contains a large amount of data. After a table is partitioned, data in the table is stored in multiple tablespaces. The database does not scan the entire table for a query.

• In MySQL mode, OceanBase Database supports the following partitioning methods: KEY, HASH, RANGE, RANGE COLUMNS, LIST, and LIST COLUMNS.

• In Oracle mode, OceanBase Database supports the following three partitioning methods: List, Range, and Hash.

  The definition of a partition in MySQL mode is different from that in Oracle mode. So, the values of the following fields vary in different modes. You need to specify the following fields based on the selected partitioning method.

  Parameter	Description
  Partitioning Method	Specifies the partitioning method. The partitioning methods supported in MySQL mode are different from those in Oracle mode. RANGE partitioning: Multiple rows with column values in an ordered, continuous, and non-overlapping range are assigned to a partition. LIST partitioning: A table is partitioned based on the enumeration values. HASH partitioning: A table is partitioned based on a given number of partitions. For a table that stores data without a clear pattern or range, you can use hash partitioning to randomly distribute values of the partition column to different partitions based on the HASH algorithm. KEY partitioning: This partitioning method is similar to HASH partitioning. The difference is that KEY partitioning supports computation of only one or more columns, and the MySQL server provides its own hash function. At least one INT type column is required for Key partitioning.
  Field	The column that is used as the partitioning key.
  Expression	Partitions are divided based on the return value of the expression. The partition expression is not supported in Oracle mode.
  Partition	Based on the value specified for Partitioning Method, you may need to specify information such as Partition Name, Partition Quantity, Upper Limit, and Value Enumeration. You can add multiple partitions and drag selected fields to adjust their order.

Step 6: Confirm the SQL statement

After you click Execute, you can view the statement on the SQL confirmation page. You can check and format the statement.

The syntax is as follows:

CREATE TABLE table_name (column_name column_type, column_name column_type,.......);

The following table describes the fields in the syntax.

Step 7: Complete the table creation

Click Execute. After the table is created, the employee table appears in the table list in the left-side navigation pane.

You can use the SELECT statement to query data in the new table.

The syntax is as follows:

SELECT
 column_name,
 column_name
FROM
 table_name [WHERE Clause] [LIMIT N] [ OFFSET M]

The following table describes the fields in the syntax.

Here is an example:

SELECT `emp_no`, `birthdate`, `name`, `gender` FROM `employee`;