Conversions in an SQL Column Definition

SQL defines four conversion strings in an SQLCOLUMNS item:

Field 8 Data generation conversion code

Field 9 Output format

Field 10 Input processing

Field 11 Update processing

SQL Conversion Codes

SQL Conversions to/from a Directly Connected Terminal

Input and Output Conversion codes are only used for an SQL query from a terminal logged directly to a Reality database. The facility to directly-connect a terminal to an SQL database is provided for administration and test purposes only. When a query is run in this way, Input and Output conversions are used to offer a level of data presentation equivalent to the corresponding English input and output conversion strings.

Data Generation

A data generation conversion, which is equivalent to a pre-processor conversion performed by English, converts data read from disk to a suitable format for SQL. Refer to field 8 in the section SQL Column Definition Fields.

Output Conversions

An output conversion, which is equivalent to an output conversion performed by English, converts data in internal format to a defined output format for display on a terminal screen, or output to a printer. Refer to field 9 in the section SQL Column Definition Fields.

Input Conversions

An input conversion, which is equivalent to an input conversion performed by English, converts the input in a query, for example, data in an INSERT or UPDATE statement, to internal form. Refer to field 10 in the section SQL Column Definition Fields.

Update Conversions

An update conversion, which has no equivalent in English, is used when updating an SQL database. It converts data from its internal form and writes it to disk in the appropriate stored format. In general this conversion is the inverse of data generation. Refer to field 11 in the section SQL Column Definition Fields.