MySQL 5.6 C API Developer Guide
This section describes C API functions other than those used for prepared statements. For information about those, see Chapter 11, C API Prepared Statement Function Descriptions.
In the descriptions here, a parameter or return value of
NULL
means NULL
in the sense
of the C programming language, not a MySQL NULL
value.
Functions that return a value generally return a pointer or an
integer. Unless specified otherwise, functions returning a pointer
return a non-NULL
value to indicate success or
a NULL
value to indicate an error, and
functions returning an integer return zero to indicate success or
nonzero to indicate an error. Note that “nonzero”
means just that. Unless the function description says otherwise,
do not test against a value other than zero:
if (result) /* correct */ ... error ... if (result < 0) /* incorrect */ ... error ... if (result == -1) /* incorrect */ ... error ...
When a function returns an error, the
Errors subsection of the function
description lists the possible types of errors. You can find out
which of these occurred by calling
mysql_errno()
. A string
representation of the error may be obtained by calling
mysql_error()
.