![]() Backslash itself (octet decimal value 92) can alternatively be represented by double backslashes. In general, to escape an octet, convert it into its three-digit octal value and precede it by a backslash. When entering bytea values in escape format, octets of certain values must be escaped, while all octet values can be escaped. Therefore, this format should probably be avoided for most new applications. But in practice it is usually confusing because it fuzzes up the distinction between binary strings and character strings, and also the particular escape mechanism that was chosen is somewhat unwieldy. If, from the point of view of the application, representing bytes as characters makes sense, then this representation can be convenient. It takes the approach of representing a binary string as a sequence of ASCII characters, while converting those bytes that cannot be represented as an ASCII character into special escape sequences. ![]() The “ escape” format is the traditional PostgreSQL format for the bytea type. The input format is different from bytea, but the provided functions and operators are mostly the same. The SQL standard defines a different binary string type, called BLOB or BINARY LARGE OBJECT. (Note that the hex format was introduced in PostgreSQL 9.0 earlier versions and some tools don't understand it.) The output format depends on the configuration parameter bytea_output the default is hex. Both of these are always accepted on input. The bytea type supports two formats for input and output: “ hex” format and PostgreSQL's historical “ escape” format. In short, binary strings are appropriate for storing data that the programmer thinks of as “ raw bytes”, whereas character strings are appropriate for storing text. Second, operations on binary strings process the actual bytes, whereas the processing of character strings depends on locale settings. Character strings disallow zero octets, and also disallow any other octet values and sequences of octet values that are invalid according to the database's selected character set encoding. ![]() First, binary strings specifically allow storing octets of value zero and other “ non-printable” octets (usually, octets outside the decimal range 32 to 126). Binary strings are distinguished from character strings in two ways. It might come useful for people working on SMS platforms.1 or 4 bytes plus the actual binary stringĪ binary string is a sequence of octets (or bytes). Here's a function to check if a string contains any 7-bit GSM characters. Getting Started Introduction A simple tutorial Language Reference Basic syntax Types Variables Constants Expressions Operators Control Structures Functions Classes and Objects Namespaces Enumerations Errors Exceptions Fibers Generators Attributes References Explained Predefined Variables Predefined Exceptions Predefined Interfaces and Classes Predefined Attributes Context options and parameters Supported Protocols and Wrappers Security Introduction General considerations Installed as CGI binary Installed as an Apache module Session Security Filesystem Security Database Security Error Reporting User Submitted Data Hiding PHP Keeping Current Features HTTP authentication with PHP Cookies Sessions Dealing with XForms Handling file uploads Using remote files Connection handling Persistent Database Connections Command line usage Garbage Collection DTrace Dynamic Tracing Function Reference Affecting PHP's Behaviour Audio Formats Manipulation Authentication Services Command Line Specific Extensions Compression and Archive Extensions Cryptography Extensions Database Extensions Date and Time Related Extensions File System Related Extensions Human Language and Character Encoding Support Image Processing and Generation Mail Related Extensions Mathematical Extensions Non-Text MIME Output Process Control Extensions Other Basic Extensions Other Services Search Engine Extensions Server Specific Extensions Session Extensions Text Processing Variable and Type Related Extensions Web Services Windows Only Extensions XML Manipulation GUI Extensions Keyboard Shortcuts ? This help j Next menu item k Previous menu item g p Previous man page g n Next man page G Scroll to bottom g g Scroll to top g h Goto homepage g s Goto search
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