Heri wrote:

Hi,

I'm starting to develop a zope products and I'm still confused on how to use ZODB.

My current application development is using RDBMS concept such as following samples:

employee table: Row First Name Last Name Age === ========== ========= === 1 Bob McBob 42 2 John Johnson 24 3 Steve Smith 38

- I can easily perform SQL statement to lookup for some information such as, total employee, who are above 30 years old, and who has the Lastname of 'Smith'. - I can easily retrieve information from multiple tables and combine it as data objects.

But how can I do this in ZODB?

I was looking at http://www.zope.org/Documentation/Books/ZDG/current/index_html but it just tell me briefly how to store objects and simple retrieval. I need to do complex queries or perform some transaction.

Can anyone help me the way to query data in ZODB?

thanks, Heri ZODB has no query language. But by using ZCatalog indexing mechanism and coupling it to Python code, you can write your own queries for data stored in ZODB.

Please others, correct my wording where incomplete/incorrect

- I can easily perform SQL statement to lookup for some information such as, total employee, who are above 30 years old, and who has the Lastname of 'Smith'. - I can easily retrieve information from multiple tables and combine it as data objects.

But how can I do this in ZODB?

1) If your data set is not too big, you can do it programmatically Python: set = folder.objectValues() results = [] for elt in set: if (elt.age > 30) and (elt.lastname=='Smith'): results.append(elt) return elt One can easily replace '30' and 'Smith' with parameters to get a more useful script. 2) Use ZCatalog for this if you have larger sets to avoid unnecessary traversals. But I suspect the larger problem is that you're thinking tabularly. Trying to make a 1-to-1 translation between an object-storage scheme and a relational-storage scheme isn't always (or maybe usually) going to work. I know no magic processes for this, unfortunately. --jcc