PHP uses BLOB to access image information instances

PHP uses BLOB to access image information instances

PHP uses BLOB to access image information instances

BLOB introduction

Mysql BLOB type

Create a database

Php file to binary code

HTML code

Read binary image

Complete php code

HTML code

Introduction to accessing image information instance BLOB using BLOB in PHP

BLOB (binary large object), a large binary object, is a container that can store binary files. In computer systems, BLOB is often the field type used to store binary files in databases. BLOB is a large file. a typical BLOB is an image or sound file. due to their size, it must be processed in a special way (for example: upload, download, or store data in a database ). According to Eric Raymond, the main idea of processing BLOB is to let the file processor (such as the database manager) ignore what the file is, but care about how to process it. However, some experts also stressed that this method of processing big data objects is a double-edged sword, which may lead to some problems, such as the storage of a large binary file, will degrade the database performance. Storing large multimedia objects in databases is a typical example of processing BLOB by applications.

Mysql BLOB type

In MySQL, BLOB is a type series, including TinyBlob, Blob, MediumBlob, and LongBlob. The only difference between these types is that the maximum size of the stored files varies.

Type size (unit: bytes)

TinyBlob	255 Max
Blob	Maximum 65 K
MediumBlob	Maximum 16 M
LongBlob	Maximum 4 GB

In linux, modify etc/my. cnf [mysqld] max_allowed_packet = 16 M // different from max_allowed_packet under [mysqldump ].

Note:Blob is a reserved word of the mysql database,Be sure not to use the field name.

Create a database

CREATE TABLE IF NOT EXISTS `myimg` ( `imgid` tinyint(3) NOT NULL AUTO_INCREMENT, `imgtype` varchar(25) NOT NULL DEFAULT '', `imgblob` mediumblob NOT NULL, PRIMARY KEY (`imgid`) )

Php file to binary code

The database reads, updates, and inserts data in the same way, so it does not need to be written. here, we only need to write the key code for uploading images to binary in PHP.

 0) {if (is_uploaded_file ($ _ FILES ['upimg '] ['tmp _ name']) {// Convert to binary $ imgBlob = addslashes (file_get_contents ($ _ FILES ['upimg '] ['tmp _ name']);}

HTML code

The file upload form must define enctype.

enctype="multipart/form-data" 

Complete Code

        
 
  
Upload a file to Blob          
  
      
 

Read binary image

To display BLOB images in a browser, we must:
1. obtain image data and types from MySQL BLOB
2. set the image type to image (image/jpg, image/gif ,...) Use the PHP header () function.
3. output the image content.

Complete php code

File name: imageView. php

 Error:SQL statement error
". Mysql_error (); $ row = mysql_fetch_array ($ result); header ("Content-type :". $ row ["imageType"]); echo $ row ["imageData"];} mysql_close ($ conn);?>

HTML code

" />

Thanks for reading this article and hope it will be helpful to php developers.
PHP BloB full instance reference network article
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