How to select columns from 2 tables in a Firebird database using zquery?

Question

I would like to display on a TDbgrid data from 2 tables on a single database file. I have tried to write sql statements like:

select "Client", "Address", "Balance" from "table1"
and "Payment" from "table2"

But it always shows this error

SQL Error: Dynamic SQL Error DQL Error code = -104 Token Unknown - line 2,
column1 and.Error -104.Invalid token The SQL: select "Client", "Address", "Balance"
from "table1"
and "Payment" from "table2" 

I don't know if it is not possible or I just got error on writing the code or is it the TDbgrid I need to modify. I searched for a zeos sql guide but I cannot find one. All I got was this: http://www.intitec.com/varios/A_ZEOS_basics_tutorial_not_only_for_firebird.pdf but still some of my questions are left unanswered.

I am using firebird database 2.5 and delphi 7.

What SQL code can I use on this?

Answer 1

Your syntax is invalid.

SELECT * FROM table1, table2

However, the above doesn't make sense either, as you're selecting every column and row from two separate tables with no means of connecting the two tables.

Table1
ColumnA    ColumnB
=======    =======
Nonsense   Here
Orange     Noise

Table2
ColumnC    ColumnD
=======    =======
Horse      Radish
No         Sense

SELECT * FROM Table1, Table2

Result:

ColumnA    ColumnB    ColumnC    ColumnD
=======    =======    =======    =======
Nonsense   Here       Horse      Radish
Orange     Noise      No         Sense

Even after your edit, there's no sense in the query.

SELECT Table1.ColumnA, Table1.ColumnB, Table2.ColumnC, Table2.ColumnD
FROM Table1, Table2

still yields the same results.

You really should look for tutorials on database programming and SQL in general. Google can help.