Oracle data types revealed: knowledge points you must know

The secret of Oracle data types: the knowledge points you must understand and specific code examples

As one of the world's leading database management systems, Oracle has great advantages in data storage and plays an important role in processing. In Oracle, data type is a very important concept, which defines the storage format, range and operation method of data in the database. This article will reveal various knowledge points of Oracle data types and demonstrate their usage and characteristics through specific code examples.

1. Common data types

1. Character data type (CHAR, VARCHAR2, CLOB)

Character data type is used to store text data , CHAR is fixed length, VARCHAR2 is variable length, and CLOB is used to store large pieces of text data. The following is some sample code:

CREATE TABLE employees (
    employee_id NUMBER,
    first_name VARCHAR2(50),
    last_name VARCHAR2(50),
    bio CLOB
);

2. Numerical data type (NUMBER, FLOAT, INTEGER)

Numeric data type is used to store numeric data, of which NUMBER can be stored Arbitrary precision numbers, FLOAT is used to store floating point numbers, INTEGER is used to store integers. The sample code is as follows:

CREATE TABLE products (
    product_id NUMBER,
    price FLOAT,
    quantity INTEGER
);

3. Date data type (DATE, TIMESTAMP)

Date data type is used to store date and time information, where DATE is used to store date , TIMESTAMP is used to store date and time. The sample code is as follows:

CREATE TABLE orders (
    order_id NUMBER,
    order_date DATE,
    delivery_time TIMESTAMP
);

2. Special data types

1. RAW type

RAW type is used to store original binary data, usually used Store multimedia data such as images and audio. The sample code is as follows:

CREATE TABLE images (
    image_id NUMBER,
    image_data RAW(1000000)
);

2. BLOB type

The BLOB type is used to store large binary data, usually used to store large files or binary objects. The sample code is as follows:

CREATE TABLE documents (
    document_id NUMBER,
    document_content BLOB
);

3. Data type conversion

In Oracle, you can use the CAST function for data type conversion to convert one data type into another data type. The sample code is as follows:

SELECT CAST('123' AS NUMBER) AS num_value
FROM dual;

4. Custom data types

In Oracle, you can use the CREATE TYPE statement to create a custom data type for storing specific data structures. The sample code is as follows:

CREATE TYPE address_type AS OBJECT (
    street VARCHAR2(50),
    city VARCHAR2(50),
    state VARCHAR2(2)
);

CREATE TABLE customers (
    customer_id NUMBER,
    customer_address address_type
);

Summary:

This article introduces knowledge points such as common data types, special data types, data type conversion and custom data types in Oracle, and uses code examples Their usage and features are demonstrated. An in-depth understanding of Oracle data types is of great significance to database design and development. I hope this article can help readers better understand and apply Oracle data types.

The above is the detailed content of Oracle data types revealed: knowledge points you must know. For more information, please follow other related articles on the PHP Chinese website!