The Interval Class

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The Interval Class

The com.informix.lang.Interval class is an Informix-specific extension to the JDBC specification from Sun Microsystems. Interval is the base class for the INTERVAL data type. Interval has two subclasses: IntervalYM (for year-month qualifiers) and IntervalDF (for day-time qualifiers). You use these subclasses to create and manipulate INTERVAL data types.

Tip:

Many of the Interval, IntervalYM, and IntervalDF constructors take a Connection object as a parameter. This passes the value of the CLIENT_LOCALE environment variable to the Interval, IntervalYM, or IntervalDF object, which allows the display of localized error messages if an exception is thrown. For more information, see Support for Localized Error Messages.

For information about the string INTERVAL formats in this section, refer to the IBM Informix: Guide to SQL Syntax.

This section discusses many of the methods you can use with the INTERVAL data types. For complete reference information, see the online reference documentation in the directory doc/javadoc/* after you install your software. (The doc directory is a subdirectory of the directory where you installed IBM Informix JDBC Driver.)

Using Variables for Binary Qualifiers

You can use string qualifiers to manipulate INTERVAL data types, but using binary qualifiers results in faster performance. The following variables are defined in the Interval base class and represent the time unit (start and end code) of a field in the binary qualifier. To use these variables, instantiate objects of the IntervalYM and IntervalDF classes, which inherit these variables from the Interval base class.

Variable: Description
TU_YEAR: Time unit for the YEAR qualifier field
TU_MONTH: Time unit for the MONTH qualifier field
TU_DAY: Time unit for the DAY qualifier field
TU_HOUR: Time unit for the HOUR qualifier field
TU_MINUTE: Time unit for the MINUTE qualifier field
TU_SECOND: Time unit for the SECOND qualifier field
TU_FRAC: Time unit for the leading FRACTION qualifier field
TU_F1: Time unit for the ending field of the first position of FRACTION
TU_F2: Time unit for the ending field of the second position of FRACTION
TU_F3: Time unit for the ending field of the third position of FRACTION
TU_F4: Time unit for the ending field of the fourth position of FRACTION
TU_F5: Time unit for the ending field of the fifth position of FRACTION

Using Interval Methods

You can use the Interval methods to extract information about binary qualifiers. To use these methods, instantiate objects of the IntervalYM and IntervalDF classes, which inherit these variables from the Interval base class.

Some of the tasks you can perform and the methods you can use follow:

Extracting the length of a qualifier:

public static byte getLength(short qualifier)

Extracting the starting field code (one of the TU_XXX variables) from a qualifier:
```
public static byte getStartCode(short qualifier)
```
Extracting the ending field code (one of the TU_XXX variables) from a qualifier:
```
public static byte getEndCode(short qualifier)
```
Obtaining the string value that corresponds to the TU_XXX value of part of an interval (for example, getFieldName(TU_YEAR) returns the string year):
```
public static String getFieldName(byte code)
```
Obtaining the entire name of the interval as a character string, taking a qualifier as input:
```
public static String getIfxTypeName(int type, 
   short qualifier)
```
Obtaining the number of digits in the FRACTION part of the INTERVAL data type:
```
public static byte getScale(short qualifier)
```
Creating a binary qualifier from a length, start code (TU_XXX), and end code (TU_XXX):
```
public static short getQualifier(byte length, byte
   startCode, byte endCode) throws SQLException
```
For example, getQualifier(4, TU_YEAR, TU_MONTH) creates a binary representation of the YEAR TO MONTH qualifier.