MySQL 5.6 C API Developer Guide
unsigned long mysql_hex_string(char *to, const char *from, unsigned long length)
This function creates a legal SQL string for use in an SQL statement. See String Literals.
The string in the from
argument is encoded
in hexadecimal format, with each character encoded as two
hexadecimal digits. The result is placed in the
to
argument, followed by a terminating null
byte.
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 byte.
The return value can be placed into an SQL statement using
either X'
or value
'0x
format. However, the return value does not include the
value
X'...'
or 0x
. The caller
must supply whichever of those is desired.
char query[1000],*end; end = strmov(query,"INSERT INTO test_table values("); end = strmov(end,"X'"); end += mysql_hex_string(end,"What is this",12); end = strmov(end,"',X'"); end += mysql_hex_string(end,"binary data: \0\r\n",16); end = strmov(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 libmysqlclient
library
and works like strcpy()
but returns a
pointer to the terminating null of the first parameter.
The length of the encoded string that is placed into
to
, not including the terminating null
character.