unsigned long mysql_hex_string(char *to, const char
*from, unsigned long length)
Description
This function is used to create a legal SQL string that you can use in a SQL statement. See Sección 9.1.1, “Cadenas de caracteres”.
The string in from
is encoded to
hexadecimal format, with each character encoded as two
hexadecimal digits. The result is placed in
to
and a terminating null byte is appended.
The string pointed to by from
must be
length
bytes long. You must allocate the
to
buffer to be at least
length*2+1
bytes long. When
mysql_hex_string()
returns, the contents of
to
is a null-terminated string. The return
value is the length of the encoded string, not including the
terminating null character.
The return value can be placed into an SQL statement using
either 0x
or value
X'
format. However, the return value does not include the
value
'0x
or X'...'
. The caller
must supply whichever of those is desired.
mysql_hex_string()
was added in MySQL
4.0.23 and 4.1.8.
Example
char query[1000],*end; end = strmov(query,"INSERT INTO test_table values("); end = strmov(end,"0x"); end += mysql_hex_string(end,"What's this",11); end = strmov(end,",0x"); end += mysql_hex_string(end,"binary data: \0\r\n",16); *end++ = ')'; if (mysql_real_query(&mysql,query,(unsigned int) (end - query))) { fprintf(stderr, "Failed to insert row, Error: %s\n", mysql_error(&mysql)); }
The strmov()
function used in the example
is included in the mysqlclient
library and
works like strcpy()
but returns a pointer
to the terminating null of the first parameter.
Return Values
The length of the value placed into to
, not
including the terminating null character.
Errors
None.
Ésta es una traducción del manual de referencia de MySQL, que puede encontrarse en dev.mysql.com. El manual de referencia original de MySQL está escrito en inglés, y esta traducción no necesariamente está tan actualizada como la versión original. Para cualquier sugerencia sobre la traducción y para señalar errores de cualquier tipo, no dude en dirigirse a mysql-es@vespito.com.