Date-Time or Interval Binary Representation

The DataBlade API supports the following SQL data types that can hold information about date-time or interval values.

The DATETIME Data Type

The SQL DATETIME data type provides the internal (binary) format of a date-time value. This data type stores an instant in time expressed as a calendar date and time of day, just a calendar date, or just a time of day. You choose how precisely a DATETIME value is stored with a qualifier. The precision can range from a year to a fraction of a second. For a detailed description of the SQL DATETIME data type, see the IBM Informix: Guide to SQL Reference.

The DATETIME data type uses a computer-independent method to encode the date or time qualifiers. It stores the information in the dtime_t structure, as follows:

typedef struct dtime {
   short dt_qual;
   dec_t dt_dec;
} dtime_t;

The dtime structure and dtime_t typedef have two parts, which the following table shows.

Field

Description

dt_qual

The qualifier of the datetime value

dt_dec

The digits of the fields of the datetime value

This field is a decimal value.

Tip:

The internal format of the DATETIME data type is often referred to as its binary representation.

The DataBlade API supports the SQL DATETIME data type with the mi_datetime data type. Therefore, the mi_datetime data type holds the binary representation of a date and/or time value.

Because the binary representation of a DATETIME (mi_datetime) value is an Informix-proprietary format, you cannot use standard system functions to perform operations on mi_datetime values. Instead, the DataBlade API provides the following support for the DATETIME data type.

The INTERVAL Data Type

The SQL INTERVAL data type holds the internal (binary) format of an interval value. It encodes a value that represents a span of time. INTERVAL types are divided into two classes: year-month intervals and day-time intervals. A year-month interval can represent a span of years and months, and a day-time interval can represent a span of days, hours, minutes, seconds, and fractions of a second. For a detailed description of the SQL INTERVAL data type, see the IBM Informix: Guide to SQL Reference.

The INTERVAL data type uses a computer-independent method to encode the interval qualifiers. It stores the information in the intrvl_t structure, as follows:

typedef struct intrvl {
   short in_qual;
   dec_t in_dec;
} intrvl_t;

The intrvl structure and intrvl_t typedef have the two parts that Table 17 shows.

The DataBlade API supports the SQL INTERVAL data type with the mi_interval data type. Therefore, an mi_interval data type holds the binary representation of an interval value.

Because the binary representation of an INTERVAL (mi_interval) value is an Informix-proprietary format, you cannot use standard system functions to perform operations on mi_interval values. Instead, the DataBlade API provides the following support for the INTERVAL data type.