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The date and time Types¶
Note: Cassandra 2.2+ is required.
The driver currently uses raw types to handle date and time because date
and time handling is often very application specific in C/C++. It currently
provides methods to handle converting Epoch (January 1, 1970) time in seconds
to and from date/time.
The date type uses an unsigned 32-bit integer (cass_uint32_t) to
represent the number of days with Epoch centered at 2^31.
Because it’s centered at Epoch it can be used to represent days before Epoch.
The time type uses a signed 64-bit integer (cass_int64_t) to
represent the number of nanoseconds since midnight and valid values are in the
range 0 to 86399999999999.
The following examples both use this schema:
CREATE TABLE date_time (key text PRIMARY KEY,
year_month_day date,
time_of_day time);
INSERTing the date and time Types¶
#include <time.h>
void insert_date_time(CassSession* session) {
CassStatement* statement = cass_statement_new("INSERT INTO date_time (key, year_month_day, time_of_day) "
"VALUES (?, ?, ?)", 3);
time_t now = time(NULL); /* Time in seconds from Epoch */
/* Converts the time since the Epoch in seconds to the 'date' type */
cass_uint32_t year_month_day = cass_date_from_epoch(now);
/* Converts the time since the Epoch in seconds to the 'time' type */
cass_int64_t time_of_day = cass_time_from_epoch(now);
cass_statement_bind_string(statement, 0, "xyz");
/* 'date' uses an unsigned 32-bit integer */
cass_statement_bind_uint32(statement, 1, year_month_day);
/* 'time' uses a signed 64-bit integer */
cass_statement_bind_int64(statement, 2, time_of_day);
CassFuture* future = cass_session_execute(session, statement);
/* Handle future result */
/* CassStatement and CassFuture both need to be freed */
cass_statement_free(statement);
cass_future_free(future);
}
SELECTing the date and time Types¶
#include <time.h>
void select_date_time(CassSession* session) {
CassStatement* statement = cass_statement_new("SELECT * FROM date_time WHERE key = ?", 1);
CassFuture* future = cass_session_execute(session, statement);
const CassResult* result = cass_future_get_result(future);
/* Make sure there's a valid result */
if (result != NULL && cass_result_row_count(result) > 0) {
const CassRow* row = cass_result_first_row(result);
/* Get the value of the "year_month_day" column */
cass_uint32_t year_month_day;
cass_value_get_uint32(cass_row_get_column(row, 1), &year_month_day);
/* Get the value of the "time_of_day" column */
cass_int64_t time_of_day;
cass_value_get_int64(cass_row_get_column(row, 2), &time_of_day);
/* Convert 'date' and 'time' to Epoch time */
time_t time = (time_t)cass_date_time_to_epoch(year_month_day, time_of_day);
printf("Date and time: %s", asctime(localtime(&time)));
} else {
/* Handle error */
}
/* CassStatement and CassFuture both need to be freed */
cass_statement_free(statement);
cass_future_free(future);
}