Create a table

Overview

A table is a data structure in a database and stores data in rows and columns.

As shown in the preceding figure, you can create a table in the following seven steps:

1. Specify the basic information.

2. Set columns.

3. Set partitioning rules.

4. Set the index.

5. Set constraints.

6. Verify the SQL statement.

7. Complete the table creation.

Procedure

In the following example, a table named employee is created in the OceanBase Developer Center (ODC) console. The table contains the emp_no, birthdate, name, and gender columns. Procedure:

Step 1: Specify the basic information.

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 get a list of tables. To create a table, click + in the upper-right corner of the table list or click Create in the top navigation bar.

In the Basic Info section, specify Table Name and Description.

Note
In MySQL mode, you also need to specify Default Character Set and Default Sorting Rule.

Step 2: Set columns.

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

The column setting section also provides three buttons.

Step 3: 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 six 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.

Step 4: Set the index.

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 the index.

The index setting section also provides three buttons.

Step 5: Set constraints.

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

ODC supports the following four 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 edit the constraint after it is configured.

• 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 edit existing constraints.

• Check Constraint: 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 Check Constraint only in Oracle mode.

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 section also provides three buttons.

Step 6: Verify the SQL statement.

Click Submit to go to the SQL Confirmation page.

You can edit the SQL statement on the SQL Confirmation page. Syntax:

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

Step 7: Complete the table creation.

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

Note
To manage a table, right-click the table name in the left-side navigation pane, and select the required operation from the context menu, which provides the following options: View, Create, **Single Table Import **, Single Table Export, Download, Mock Data, Open SQL Window, Copy, Rename, Delete, and Refresh.

For more information, see Manage table data.

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

Syntax:

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

Example:

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

Related topics

• Create a view
• Create a function
• Create a stored procedure
• Create a sequence
• Create a program package
• Create a trigger
• Create a type
• Create a synonym