You can use a function expression to perform various operations on column data or to obtain information from the database server about the contents of one or more columns. A function expression requires an argument or parameter. For all three of these function expressions, the argument is the name of a column that is stored on an optical platter. For more information on function expressions and a complete list of other function expressions, see the IBM Informix: Guide to SQL Syntax.
Use the DESCR(), FAMILY(), and VOLUME() function expressions to obtain information about TEXT or BYTE data columns that are stored on optical platters.
Function Expressions: |--+-| Function Expressions see SQLS |-+------------------------| +-DESCR(column name)----------------+ +-FAMILY(column name)---------------+ '-VOLUME(column name)---------------'
| Element | Purpose | Restrictions | Syntax |
|---|---|---|---|
| column name | The name of the TEXT or BYTE data column on which the function operates | The column must be stored on an optical platter. | Identifier segment; see IBM Informix: Guide to SQL Syntax. |
The DESCR() function returns TEXT data that is the encoded descriptor for the TEXT or BYTE data column. The FAMILY() function returns the name of the optical family in which a column is stored. The VOLUME() function returns the number of the volume on which a column is stored. All three functions are valid only for data stored on an optical platter. They are valid whether the TEXT and BYTE data is stored sequentially or in clusters. An error message is returned if the functions are used on a column that is not stored on an optical platter.
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