📄 blob-1.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><HTML><HEAD> <META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9"> <TITLE>BLOBs for PHPLIB: BLOB (Binary Large OBjects)</TITLE> <LINK HREF="blob.html#toc1" REL=contents></HEAD><BODY>NextPrevious<A HREF="blob.html#toc1">Contents</A><HR><H2><A NAME="s1">1. BLOB (Binary Large OBjects)</A></H2><P>This chapter is intended to give you a quick introduction to BLOBs, their interface as proposed for PHPLIB.<P><H2><A NAME="ss1.1">1.1 Defining the problem</A></H2><P>Achieving the goal of creating portable applications is hindered bythe fact that no portable way of storing large amount of dataexists.<P>Every database vendor defines his own application programminginterface (API) to access binary large objects, or uses other, non-standard ways to enable the use of BLOBs.<P>Enhancing the existing vendor neutral support for databases inPHPLIB to also include BLOB support could be a short-term solutionto the problem.<P><H2><A NAME="ss1.2">1.2 Proposed extension API</A></H2><P><P>An overview over the function calls follows.<P><DL><DT><B>blob_create()</B><DD><P><P>This will create a new BLOB and return its ID. If it is impossibleto create a new BLOB, this function will <CODE>halt()</CODE> the executionand generate an error message.<P><DT><B>blob_open($ID)</B><DD><P><P>Opens the specified BLOB for reading and writing and returns true or falseon success or failure, respectively.<P><DT><B>blob_close($ID)</B><DD><P><P>Closes the referenced BLOB. Do not forget this - it might be necessaryfor some databases or you might face data loss.<P><DT><B>blob_delete($ID)</B><DD><P><P>Deletes the specified BLOB. All associated resources are freed.The BLOB must not be referenced at a later time.<P><DT><B>blob_read($ID)</B><DD><P><P>Reads the entire data of BLOB and returns it.<P><DT><B>blob_write($ID, $DATA)</B><DD><P><P>Overwrites the whole BLOB with $DATA. <P></DL><P><H2><A NAME="ss1.3">1.3 Design notes</A></H2><P>The goal was to create a vendor neutral API which could be implementedeasily with most databases. Eventually, it should provide a"fallback" mode enabling the user to utilize BLOBs even if thedatabase does not support BLOBs natively. Keep in mind that itshould be able to cover as many databases as possible and thereforeonly implements a subset of functionality provided by moderndatabases.<P><HR>NextPrevious<A HREF="blob.html#toc1">Contents</A></BODY></HTML>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -