Introduction to the differences and usage of Blob and Clob data types in Oracle

The Blob and Clob data types in Oracle database play an important role in storing large data objects. Blob is used to store binary data, such as pictures, audio or video files, while Clob is used for text data, such as long text, HTML pages, etc. This article will introduce in detail the difference between Blob and Clob data types and how to use them, while providing specific code examples.

1. Blob data type:

The Blob data type is used to store binary large objects. In Oracle database, the Blob type supports storing up to 4GB of binary data. The Blob type is usually used to store binary data such as images, audio, and video. Following is the sample code for Blob data type:

-- 创建包含Blob类型字段的表
CREATE TABLE Blob_Table (
    id NUMBER PRIMARY KEY,
    image_data BLOB
);

-- 插入Blob数据
INSERT INTO Blob_Table (id, image_data) VALUES (1, EMPTY_BLOB());

-- 更新Blob数据
UPDATE Blob_Table SET image_data = (SELECT * FROM BFILE('IMG_DIR', 'example.jpg')) WHERE id = 1;

-- 查询Blob数据
SELECT image_data FROM Blob_Table WHERE id = 1;

2. Clob data type:

Clob data type is used to store character large objects. The Clob type supports storing up to 4GB of text data. The Clob type is usually used to store character data such as long text and HTML pages. The following is a sample code for Clob data type:

-- 创建包含Clob类型字段的表
CREATE TABLE Clob_Table (
    id NUMBER PRIMARY KEY,
    text_data CLOB
);

-- 插入Clob数据
INSERT INTO Clob_Table (id, text_data) VALUES (1, TO_CLOB('This is a sample text data'));

-- 更新Clob数据
UPDATE Clob_Table SET text_data = TO_CLOB('Updated text data') WHERE id = 1;

-- 查询Clob数据
SELECT text_data FROM Clob_Table WHERE id = 1;

Through the above sample code, we can see how to create tables in Oracle database and use Blob and Clob data types to store different types of large object data. Blob is used to store binary data, while Clob is used to store character data. In practical applications, choosing an appropriate storage method based on the characteristics of the data type can better meet business needs.

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