Mega Code Archive

 

Categories / Delphi / ADO Database

 

Hetergenious joins

Question: Hetergenious joins: How do I join files from differing alias (heterogeneous joins) using a SQL statment? Answer: For each server table, a connection must exist before the query is executed. A TDatabase can be used to establish the connection. The SQL statement must use real alias names, as set up in the BDE configuration utility, not DatabaseName properties from a TDatabase. The SQL syntax should be formatted as follows: a double quote, a colon, a real alias name, a colon, the table name, and a double quote. See example below. Leave the DatabaseName property of the TQuery blank, unless the alias is local. For example, specifying DBDEMOS in the Query's DatabaseName property will work, but using IBLOCAL will cause a general SQL error. Example: SELECT A.ITEMNO, B.VENDORNO FROM ":DBDEMOS:ITEMS" A, ":IBLOCAL:VENDORS" B WHERE A.VENDORNO = B.VENDORNO