my_ulonglong
mysql_affected_rows(MYSQL *mysql)
mysql_affected_rows()
may be
called immediately after executing a statement with
mysql_real_query()
or
mysql_query()
. It returns the
number of rows changed, deleted, or inserted by the last
statement if it was an UPDATE
,
DELETE
, or
INSERT
. For
SELECT
statements,
mysql_affected_rows()
works
like mysql_num_rows()
.
For UPDATE
statements, the
affected-rows value by default is the number of rows actually
changed. If you specify the
CLIENT_FOUND_ROWS
flag to
mysql_real_connect()
when
connecting to mysqld, the affected-rows
value is the number of rows “found”; that is,
matched by the WHERE
clause.
For REPLACE
statements, the
affected-rows value is 2 if the new row replaced an old row,
because in this case, one row was inserted after the duplicate
was deleted.
For
INSERT
... ON DUPLICATE KEY UPDATE
statements, the
affected-rows value per row is 1 if the row is inserted as a
new row, 2 if an existing row is updated, and 0 if an existing
row is set to its current values. If you specify the
CLIENT_FOUND_ROWS
flag, the affected-rows
value is 1 (not 0) if an existing row is set to its current
values.
Following a CALL
statement for
a stored procedure,
mysql_affected_rows()
returns
the value that it would return for the last statement executed
within the procedure, or 0
if that
statement would return -1
. Within the
procedure, you can use
ROW_COUNT()
at the SQL level to
obtain the affected-rows value for individual statements.
In MySQL 5.7,
mysql_affected_rows()
returns
a meaningful value for a wider range of statements. For
details, see the description for
ROW_COUNT()
in
Information Functions.
An integer greater than zero indicates the number of rows
affected or retrieved. Zero indicates that no records were
updated for an UPDATE
statement, no rows matched the WHERE
clause
in the query or that no query has yet been executed. -1
indicates that the query returned an error or that, for a
SELECT
query,
mysql_affected_rows()
was
called prior to calling
mysql_store_result()
.
Because mysql_affected_rows()
returns an unsigned value, you can check for -1 by comparing
the return value to (my_ulonglong)-1
(or to
(my_ulonglong)~0
, which is equivalent).