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    1. General Information
    2. MySQL Installation
    3. Tutorial Introduction
    4. Database Administration
    5. MySQL Optimisation
    6. MySQL Language Reference
    7. MySQL Table Types
    8. MySQL APIs
    9. Extending MySQL
    378 MySQL Technical Reference for Version 4.0.3 page 558.  In Perl,  you can use the  quote  method of the  DBI  package to convert special characters to the proper escape sequences.  See Section 8.2.2 [Perl DBI Class], page 540. You  should  use  an  escape  function  on  any  string  that  might  contain  any  of  the  special characters listed above! Alternatively, many MySQL APIs provide some sort of placeholder capability that allows you to insert special markers into a query string, and then bind data values to them when you issue the query.  In this case, the API takes case of escaping special characters in the values for you automatically. 6.1.1.2  Numbers Integers are represented as a sequence of digits. Floats use `.' as a decimal separator. Either type of number may be preceded by `-' to indicate a negative value. Examples of valid integers: 1221 0 -32 Examples of valid oating-point numbers: 294.42 -32032.6809e+10 148.00 An  integer  may  be  used  in  a   oating-point  context;  it  is  interpreted  as  the  equivalent oating-point number. 6.1.1.3  Hexadecimal Values MySQL supports hexadecimal values.  In numeric context these act like an integer (64-bit precision).  In string context these act like a binary string where each pair of hex digits is converted to a character: mysql> SELECT x'FF' -> 255 mysql> SELECT 0xa+0; -> 10 mysql> SELECT 0x5061756c; -> Paul The x'hexstring' syntax (new in 4.0) is based on ANSI SQL and the 0x syntax is based on ODBC. Hexadecimal strings are often used by ODBC to supply values for BLOB columns. You can convert a string or a number to hexadecimal with the HEX() function. 6.1.1.4  NULL Values The NULL value means \no data" and is di erent from values such as 0 for numeric types or the empty string for string types.  See Section A.5.3 [Problems with NULL], page 646.
     

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