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DataServer for Microsoft SQL Server
Initial Programming Considerations : Database design issues : Code pages : Client code page
Client code page
The Internal Code Page (-cpinternal) startup parameter determines the code page that the OpenEdge client uses when it manipulates data in memory. If the OpenEdge client uses a different code page from the code page set in the schema holder, the DataServer translates between the two code pages, so you must verify that the convmap.cp file contains a conversion table for the client and the code page setting in the schema holder. Suppose, for example, that you set the schema holder to code page ibm850 and the client uses code page iso8859-1. The convmap.cp file must include a table that converts from ibm850 to iso8859-1 and from iso8859-1 to ibm850. If convmap.cp does not include the appropriate table, you can define your own conversion table.
OpenEdge also allows you to define your own collation tables; however, customized collation tables only take effect after data source collation when you use the DataServer to access a MS SQL Server data source. The data source collation tables, not the OpenEdge collation tables, have first priority when you perform comparisons and sorts. After performing comparisons and sorts, the OpenEdge client may sort out records that do not conform to the requirements of your customized collation tables.
For example, if you use the default code page 1252 and the default case insensitive sort ordering with a MS SQL Server data source, collation of the tilde character (~), which is ASCII character 126, sorts before all the alphanumeric characters (0-9, a-z). If you were to select data from a character column name with the following:
select * from table where name <=CHR(126) (the equivalent of ~)
MS SQL Server returns records with columns that begin with a tilde character but no alphanumeric records, since ASCII character 126 is sorted below alphanumeric characters in this MS SQL Server collation.
Normally, the default OpenEdge collation sorts a tilde character above all alphanumeric characters. Therefore, in order for the above example to exhibit OpenEdge-like behavior and return alphanumeric records as well as records beginning with the tilde, the MS SQL Server sort order for this code page would need to be modified accordingly.
Conversely, if you execute the opposite:
select * from table where name >=CHR(126)
MS SQL Server returns records with columns that begin with a tilde character followed by all that begin with alphanumeric characters. However, the default OpenEdge collation, which sorts the tilde higher than all the alphanumeric characters, would omit records beginning with alphanumeric characters and only return records beginning with the tilde character.
To get the full result set returned from MS SQL Server from the OpenEdge client would require modifying the collation table associated with the OpenEdge code page and weighting it to match the MS SQL Server sort order.
For a complete discussion of how OpenEdge handles code-page issues, see OpenEdge Development: Internationalizing Applications.