Character code conversions under the OLE DB Provider for AS/400 and VSAM are controlled by a hierarchy of parameters. When connecting to mainframes all of these parameters are controlled on the PC. However, when connecting to data sources on the AS/400, parameter settings on the AS/400 as well as parameter settings on the PC can be involved.
The Character Code Set Identifier (CCSID) used by the host for a data source can be specified in several locations. The Host CCSID setting used by the OLE DB Provider must bet set to match the CCSID actually used on the host otherwise data loss will occur. Note that some AS/400 systems default to a CCSID of 937 rather than 37 for enabling double-byte character sets (DBCS).
The following table illustrates the separate hierarchy controlling the Host CCSID parameter on the SNA client, AS/400 host, and mainframe host.
| SNA client | AS/400 host | Mainframe host |
|---|---|---|
| SNA OLE DB Provider (registry setting) | System (DSPSYSVAL, QCCSIP) | None. Determined by the Data Description (HCD file) on the SNA Client. |
| Data Source (registry setting) | User identifier (wrkusrprf) | |
| Data Description (HCD file) | Job (dspjob, crtjobd) | |
| File (dspfd, crtpf) | ||
| Column (dspffd) |
Note that only those fields in a Data Source that contain character data will be affected by the Host CCSID parameters and character conversions.