You have two way rddado and rddsql
I suggest you see sample contrib/rddsql
about rddado way unsuggested here an Italian document
http://www.gio22.com/harbour/tutorial/mysql01.pdf
With rdd you can use a different use program and maintain rest of
dbase priogram unchanged
USE giovanni VIA "ADORDD" TABLE "mytable" MYSQL FROM "db4free.net"
USER "username" PASSWORD "***"
rddado is limited to windows and require a right distribution of mdac
done my microsoft, e the odbc driver
rddsql allow use more sql oriented command
AFAIK RDDSQL talk directly with the sql language so in not neccessary
this is message post by Mindaugas Kavaliauskas on this list
same capability like deleted(),recno() are not aivable but can be
emulated adding special field..
Code:
===================================================================
Simple SQL Interface for Harbour
1. Introduction
Simple SQL interface implements accessing SQL query result via RDD
interface. It is not intended to be replacement for "transparent" move of
DBFCDX application to SQL world.
I want to discuss this in more detail. Many current RDDs for SQL servers
(ex. SQLRDD from xHarbour.com) tries to make a feeling you are working with
DBF file, but not with SQL database. SQL server does not support many
features, ex. RECNO(), deleted flag, file locks, record locks. These RDDs
are emulating these features to make feeling of DBF. DELETED() function is
emulated by creating additional table columns to store delete flag. Some
"hidden system" tables are used to register locking operations and emulate
record and file locks in DBF style. The idea of SQL query is also lost. If
you do a simple loop
DBUSEAREA(, "select * from my_table")
DO WHILE ! EOF()
somefunc( FIELD->some_sql_field )
DBSKIP()
ENDDO
RDD usualy will read SQL rows in portions, let's say 100 records per query.
So, hidden queries are generated. If you are using indexes these queries
are really complicated. Let's have index on FIELD1 + STR(FIELD2). A seek to
value cValue1 + STR(nValue2) will generate a query like:
SELECT * FROM my_table
WHERE (FIELD1 == cValue1 and FIELD2 >= nValue2) or FIELD1 > cValue1
ORDER BY FIELD1, FIELD2, _RECNO
LIMIT 100
After evaluation of first 100 cached records, next query will be generated:
SELECT * FROM my_table
WHERE (FIELD1 == cLastField1 and FIELD2 == nLastValue2 and
_RECNO > nLastRecno) or
(FIELD1 == cLastField1 and FIELD2 > nLastValue2) or
FIELD1 > cLastValue1
ORDER BY FIELD1, FIELD2, _RECNO
LIMIT 100
To optimize these queries the SQL index expresion should be
"FIELD1,FIELD2,_RECNO", but not "FIELD1,FIELD2" as written in INDEX ON
command.
"Simple SQL interface" is too long to repeat every time I want to
address this library. I'll also use acronym "SSI" to address it.
The idea of SSI is different. It does not make hidden queries. All
queries should be made explicitly by programmer. SSI gives access to query
result via RDD interface, it does not tries to emulate DBF and be
"plug-and-play" solution for DBF to SQL migration. If you do
DBUSEAREA(, "select * from my_table")
all query (it could contain millions of records!) will be cached.
The features of SSI approach are:
- It's possible to access SQL database of other applications. Other
applications usualy does not follow agreement of "plug-and-play" SQL drivers
about additional DELETED column, _RECNO in the end of index expression, etc.
Access of SQL database of other applications is sometimes not possible.
- It's query oriented. That means a simple DO WHILE ! EOF() loop will iterate
each records once and only once. This is not true for "plug-and-play" SQL
drivers, if indexing is used. Just like in the case of loop over DBF file.
It is not guaranteed that all records are included! Yes! If key value of the
first record in index is changed to be the last record in index during the
phase of record processing, DO WHILE ! EOF() loop will iterate only this
single records even if the database contains millions of records. Your sould
do FLOCK() on DBF to guarantee the records are not changed. Do you use FLOCK()
before readonly DO WHILE ! EOF() loops? :)
2. Architecture
+-------------+
| |
| SQLMIX RDD |
| |
+-------------+
| ^
V |
+-------------+ +---------+
| |--->| |
| SQLBASE RDD | | SDD |
| |<---| |
+-------------+ +---------+
SQLBASE RDD implements basic functionality for accessing SQL query result
via RDD interface. This RDD could be used, if indexing of query result is not
necessary or all indexing is done by SQL server (by using ORDER BY clause).
SQLMIX RDD implements indexing of query result. This indexing is not
related to SQL server ORDER BY clause. SQLMIX do indexing of the query on the
client side.
SDD is acronym for Sql Database Driver. RDD is used to implement access
of different database formats like DBF, SDF, etc. SDD is used to implement
access of different SQL databases. Every SQL server (MySQL, PostgreSQL, etc.)
has a corresponding SDD. SDD driver implements a specific part of data
exchange interface between SQLBASE and SQL server.
A few additional functions are also implemented, ex. HB_SQLCONNECT().
Usualy these functions are just a shorter version of corresponding RDDINFO()
call.
3. Modifying database
SSI presents a query result via RDD interface and generates no hidden
SQL queries. So, how database can be changed? Does DBAPPEND() and FIELDPUT()
works, or is it readonly SQL interface?
DBAPPEND(), FIELDPUT() and other similiar functions work on cached query
result, i.e. query can be appended by new rows and field values can be
changed, but SQL database is not changed. DBCREATE() function can also be
used to create an "empty query result" but no table is created on SQL server.
So, SSI can also be used as implementation of "array RDD".
The programmer must call SQL command explicitly to modify SQL tables.
SSI provides a method to detect which cached rows was changed or appended
I suggest you download last version of harbour
Harbour 2.0.0beta3 (r12422) source archives and Windows binary
releases are available for download here:
http://syenar.hu/harbour/
Make sure to check INSTALL doc "QUICK START" section and visit
our user forums at:
http://sourceforge.net/apps/phpbb/harbour-project/
2009/9/9 DANILO SERON <[email protected]>:
> ¿ http://packages.debian.org/es/sid/dbf2mysql ?
>
>
>
> --- El mar 8-sep-09, [email protected]
> <[email protected]> escribió:
>
> De: [email protected]
> <[email protected]>
> Asunto: Harbour-users Digest, Vol 15, Issue 1
> A: [email protected]
> Fecha: martes, 8 septiembre, 2009, 1:00 pm
>
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> 1. mysql connect (jim clark)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 8 Sep 2009 20:24:02 +0530
> From: jim clark <[email protected]>
> Subject: [Harbour-users] mysql connect
> To: [email protected]
> Message-ID:
> <[email protected]>
> Content-Type: text/plain; charset=ISO-8859-1
>
> hi, i am new to harbour and xbase. i have been using mysql and python
> based mvc for connecting to mysql for my database needs. can anybody point
> me to any tutorials for doing the same with harbour. i got my hands on my
> dad's old dbase reference guide and i have been able to do some simple db
> work. but i unable to find any way to connect to mysql.
>
> Regards
>
> utkarsh
>
>
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