(mysql.info.gz) mysql_stmt_fetch
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(mysql.info.gz) mysql_stmt_insert_id
(mysql.info.gz) C API Prepared statement functions
(mysql.info.gz) mysql_stmt_fetch_column
22.2.7.13 `mysql_stmt_fetch()'
..............................
`int mysql_stmt_fetch(MYSQL_STMT *stmt)'
Description
...........
`mysql_stmt_fetch()' returns the next row in the result set. It can be
called only while the result set exists, that is, after a call to
`mysql_stmt_execute()' that creates a result set or after
`mysql_stmt_store_result()', which is called after
`mysql_stmt_execute()' to buffer the entire result set.
`mysql_stmt_fetch()' returns row data using the buffers bound by
`mysql_stmt_bind_result()'. It returns the data in those buffers for
all the columns in the current row set and the lengths are returned to
the `length' pointer.
All columns must be bound by the application before calling
`mysql_stmt_fetch()'.
If a fetched data value is a `NULL' value, the `*is_null' value of the
corresponding `MYSQL_BIND' structure contains TRUE (1). Otherwise, the
data and its length are returned in the `*buffer' and `*length'
elements based on the buffer type specified by the application. Each
numeric and temporal type has a fixed length, as listed in the
following table. The length of the string types depends on the length
of the actual data value, as indicated by `data_length'.
*Type* *Length*
`MYSQL_TYPE_TINY' 1
`MYSQL_TYPE_SHORT' 2
`MYSQL_TYPE_LONG' 4
`MYSQL_TYPE_LONGLONG' 8
`MYSQL_TYPE_FLOAT' 4
`MYSQL_TYPE_DOUBLE' 8
`MYSQL_TYPE_TIME' `sizeof(MYSQL_TIME)'
`MYSQL_TYPE_DATE' `sizeof(MYSQL_TIME)'
`MYSQL_TYPE_DATETIME' `sizeof(MYSQL_TIME)'
`MYSQL_TYPE_STRING' `data length'
`MYSQL_TYPE_BLOB' `data_length'
This function was added in MySQL 4.1.2.
Return Values
.............
*Return Value* *Description*
0 Successful, the data has been fetched to
application data buffers.
1 Error occurred. Error code and message can be
obtained by calling `mysql_stmt_errno()' and
`mysql_stmt_error()'.
`MYSQL_NO_DATA' No more rows/data exists
`MYSQL_DATA_TRUNCATED' Data truncation occurred
`MYSQL_DATA_TRUNCATED' is not returned unless truncation reporting is
enabled with `mysql_options()'. To determine which parameters were
truncated when this value is returned, check the `error' members of the
`MYSQL_BIND' parameter structures.
Errors
......
`CR_COMMANDS_OUT_OF_SYNC'
Commands were executed in an improper order.
`CR_OUT_OF_MEMORY'
Out of memory.
`CR_SERVER_GONE_ERROR'
The MySQL server has gone away.
`CR_SERVER_LOST'
The connection to the server was lost during the query.
`CR_UNKNOWN_ERROR'
An unknown error occurred.
`CR_UNSUPPORTED_PARAM_TYPE'
The buffer type is `MYSQL_TYPE_DATE', `MYSQL_TYPE_TIME',
`MYSQL_TYPE_DATETIME', or `MYSQL_TYPE_TIMESTAMP', but the data
type is not `DATE', `TIME', `DATETIME', or `TIMESTAMP'.
`'
All other unsupported conversion errors are returned from
`mysql_stmt_bind_result()'.
Example
.......
The following example demonstrates how to fetch data from a table using
`mysql_stmt_result_metadata()', `mysql_stmt_bind_result()', and
`mysql_stmt_fetch()'. (This example expects to retrieve the two rows
inserted by the example shown in `mysql_stmt_execute()'
mysql_stmt_execute.) The `mysql' variable is assumed to be a valid
connection handle.
#define STRING_SIZE 50
#define SELECT_SAMPLE "SELECT col1, col2, col3, col4 FROM test_table"
MYSQL_STMT *stmt;
MYSQL_BIND bind[4];
MYSQL_RES *prepare_meta_result;
MYSQL_TIME ts;
unsigned long length[4];
int param_count, column_count, row_count;
short small_data;
int int_data;
char str_data[STRING_SIZE];
my_bool is_null[4];
/* Prepare a SELECT query to fetch data from test_table */
stmt = mysql_stmt_init(mysql);
if (!stmt)
{
fprintf(stderr, " mysql_stmt_init(), out of memory\n");
exit(0);
}
if (mysql_stmt_prepare(stmt, SELECT_SAMPLE, strlen(SELECT_SAMPLE)))
{
fprintf(stderr, " mysql_stmt_prepare(), SELECT failed\n");
fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
exit(0);
}
fprintf(stdout, " prepare, SELECT successful\n");
/* Get the parameter count from the statement */
param_count= mysql_stmt_param_count(stmt);
fprintf(stdout, " total parameters in SELECT: %d\n", param_count);
if (param_count != 0) /* validate parameter count */
{
fprintf(stderr, " invalid parameter count returned by MySQL\n");
exit(0);
}
/* Fetch result set meta information */
prepare_meta_result = mysql_stmt_result_metadata(stmt);
if (!prepare_meta_result)
{
fprintf(stderr,
" mysql_stmt_result_metadata(), returned no meta information\n");
fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
exit(0);
}
/* Get total columns in the query */
column_count= mysql_num_fields(prepare_meta_result);
fprintf(stdout, " total columns in SELECT statement: %d\n", column_count);
if (column_count != 4) /* validate column count */
{
fprintf(stderr, " invalid column count returned by MySQL\n");
exit(0);
}
/* Execute the SELECT query */
if (mysql_stmt_execute(stmt))
{
fprintf(stderr, " mysql_stmt_execute(), failed\n");
fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
exit(0);
}
/* Bind the result buffers for all 4 columns before fetching them */
memset(bind, 0, sizeof(bind));
/* INTEGER COLUMN */
bind[0].buffer_type= MYSQL_TYPE_LONG;
bind[0].buffer= (char *)&int_data;
bind[0].is_null= &is_null[0];
bind[0].length= &length[0];
/* STRING COLUMN */
bind[1].buffer_type= MYSQL_TYPE_STRING;
bind[1].buffer= (char *)str_data;
bind[1].buffer_length= STRING_SIZE;
bind[1].is_null= &is_null[1];
bind[1].length= &length[1];
/* SMALLINT COLUMN */
bind[2].buffer_type= MYSQL_TYPE_SHORT;
bind[2].buffer= (char *)&small_data;
bind[2].is_null= &is_null[2];
bind[2].length= &length[2];
/* TIMESTAMP COLUMN */
bind[3].buffer_type= MYSQL_TYPE_TIMESTAMP;
bind[3].buffer= (char *)&ts;
bind[3].is_null= &is_null[3];
bind[3].length= &length[3];
/* Bind the result buffers */
if (mysql_stmt_bind_result(stmt, bind))
{
fprintf(stderr, " mysql_stmt_bind_result() failed\n");
fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
exit(0);
}
/* Now buffer all results to client */
if (mysql_stmt_store_result(stmt))
{
fprintf(stderr, " mysql_stmt_store_result() failed\n");
fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
exit(0);
}
/* Fetch all rows */
row_count= 0;
fprintf(stdout, "Fetching results ...\n");
while (!mysql_stmt_fetch(stmt))
{
row_count++;
fprintf(stdout, " row %d\n", row_count);
/* column 1 */
fprintf(stdout, " column1 (integer) : ");
if (is_null[0])
fprintf(stdout, " NULL\n");
else
fprintf(stdout, " %d(%ld)\n", int_data, length[0]);
/* column 2 */
fprintf(stdout, " column2 (string) : ");
if (is_null[1])
fprintf(stdout, " NULL\n");
else
fprintf(stdout, " %s(%ld)\n", str_data, length[1]);
/* column 3 */
fprintf(stdout, " column3 (smallint) : ");
if (is_null[2])
fprintf(stdout, " NULL\n");
else
fprintf(stdout, " %d(%ld)\n", small_data, length[2]);
/* column 4 */
fprintf(stdout, " column4 (timestamp): ");
if (is_null[3])
fprintf(stdout, " NULL\n");
else
fprintf(stdout, " %04d-%02d-%02d %02d:%02d:%02d (%ld)\n",
ts.year, ts.month, ts.day,
ts.hour, ts.minute, ts.second,
length[3]);
fprintf(stdout, "\n");
}
/* Validate rows fetched */
fprintf(stdout, " total rows fetched: %d\n", row_count);
if (row_count != 2)
{
fprintf(stderr, " MySQL failed to return all rows\n");
exit(0);
}
/* Free the prepared result metadata */
mysql_free_result(prepare_meta_result);
/* Close the statement */
if (mysql_stmt_close(stmt))
{
fprintf(stderr, " failed while closing the statement\n");
fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
exit(0);
}
Info Catalog
(mysql.info.gz) mysql_stmt_insert_id
(mysql.info.gz) C API Prepared statement functions
(mysql.info.gz) mysql_stmt_fetch_column
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