Difference between revisions of "ODBC: Features and Limitations"
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Revision as of 10:36, 26 March 2009
Contents
Supported ODBC SQL data types
| fSqlType | Recital/SQL Data Type |
|---|---|
| SQL_CHAR | CHAR(n) |
| SQL_VARCHAR | VARCHAR(n) |
| SQL_LONGVARCHAR | LONG VARCHAR |
| SQL_NUMERIC | DECIMAL(precision, scale) |
| SQL_NUMERIC | NUMERIC(precision, scale) |
| SQL_NUMERIC | SMALLINT |
| SQL_INTEGER | INTEGER |
| SQL_REAL | REAL |
| SQL_FLOAT | FLOAT |
| SQL_NUMERIC | DOUBLE PRECISION |
| SQL_BIT | BIT |
| SQL_TINYINT | TINYINT |
| SQL_NUMERIC | BIGINT |
| SQL_SHORT | SHORT(precision, scale) |
| SQL_DATE | DATE |
| SQL_BIT | LOGICAL |
| SQL_LONGVARCHAR | MEMO |
| SQL_NUMERIC | BYTE |
| SQL_LONGVARBINARY | OBJECT |
| SQL_DATETIME | DATETIME |
| SQL_CURRENCY | CURRENCY |
| SQL_ZONED | ZONED |
Query optimization
Full query optimization is supported on the server using "index restriction" query optimization. Make sure you have the required indexes set up.
recital
You can execute any Recital non user-interface command from the ODBC driver by prefixing the command in SQLExecute() or SQLExecDirect() with the keyword 'recital'. For example:
SQLExecDirect(hstmt, "recital do myproc", cbSqlStr);
Any output can then be accessed using SQLFetch() calls. You can control shared access with this command. For example:
SQLExecDirect(hstmt, "recital set exclusive off", cbSqlStr);
Data types
All Recital data types are supported (including memos). These can be specified in the CREATE TABLE command.
Parameters
Character and binary values supplied for parameterized queries are limited to 255 bytes.
Qualifiers and owners
Qualifiers or owners are not allowed on databases or tables.
Case sensitivity
Column and table names are not case sensitive. String data comparisons are case sensitive.
Exclusive access
By default all tables are opened shareable on the server. If you do not want this then:
- Call SQLExecute(hstmt, "recital set exclusive on") before opening a table.
- Set the 'useoptions' string in the sysodbc.ini file on the server to 'exclusive' for each table that you require non-shareable access to.
- Add the command set exclusive on to the config.db file. This will cause all tables to be opened exclusively.
Memo / long varchar
Memo fields are seen as SQL LONG VARCHAR columns, and default to a maximum of 64k characters. This can be altered by setting the 'maxvarcharsize' entry in recital.ini on the client to the required value. Be careful when making this too large as performance will be unduly affected.
Tracing
ODBC driver and Recital Server interaction can be debugged on the client by selecting the 'Trace RSI calls' checkbox in the SQLDriverConnect() dialog.
Logging
Recital Server activity can be debugged by setting the 'logging' string in recital.ini or see the Recital Server Configuration Guide for information about setting up logging on the server. The resultant file on the server can be viewed using a standard text editor.
