Hi,

Try to use a $ string search like a condition between two tables,
fire a "SQL: Internal Error"

CLEAR

CREATE CURSOR aaa ( id C(1),s1 C(5))
INSERT INTO aaa VALUES ('a','a')
INSERT INTO aaa VALUES ('b','ba')

SYS(3054,11)
ON ERROR ? MESSAGE()

* VFP try to optimize the join, build a temp index for do this, 
* but this operation is impossible, 
* catch it and fire a SQL: Iternal Error

SELECT * FROM aaa t1,aaa t2 WHERE t1.id $ t2.s1 
SELECT * FROM aaa t1 JOIN aaa t2 ON t1.id $ t2.s1 
SELECT * FROM aaa t1 JOIN aaa t2 ON .T. WHERE t1.id $ t2.s1 

*  Not optimizable Cartesian Product is ok
SELECT * FROM aaa t1 JOIN aaa t2 ON t2.s1 LIKE "%"+t1.id+"%"
SELECT * FROM aaa t1 JOIN aaa t2 ON AT(t1.id,t2.s1)>0

ON ERROR
SYS(3054,0)

Fabio