Query with Dynamic SQL

Question

Hello,
I would like to create a Dynamic SQL in which change is the name of the table according to the outcome of the first SQL. This is possible?
'WITH TABLE_X AS(SELECT LEVEL LVL FROM DUAL CONNECT BY LEVEL <= 12)' ||
'SELECT A.COL1, A.COL2, B.COL1, B.COL7'                              ||
'  FROM TABLE_A' || TABLE_X.LVL || ' A'                              ||
'     , TABLE_B' || TABLE_X.LVL || ' B'                              ||
' WHERE A.COL1 = B.COL1 AND ...    'tables in database
TABLE_A1
TABLE_A2
TABLE_A12
TABLE_B1
TABLE_B2
TABLE_B12let me know how I can do this
Regards

Answer 1

Hi,
Sorry, I don't see what you're trying to do.
"Dynamic SQL" is really a mis-nomer. The number of tables and columns in a query, and their names, must be spelled out when the statement is compiled. There is nothing dynamic about it.
In dynamic SQL, a PL/SQL procedure or another query writes all or part of query just milliseconds before it is compiled, typically using data taken from tables or supplied by a user right then.
For example, consider this static query:
SELECT     a.col1, a.col2, b.col1, b.col7
FROM     table_1     a
,     table_2 b
WHERE     a.col1 = b.col1;Now, say the 1 in "table_1" and the 2 in "table_2" are variables, x and y, that you will want to look up from another table every time you run this query. You can make it dynamic like this:
sql_txt := 'SELECT  a.col1, a.col2, b.col1, b.col7 '
     || 'FROM    table_' || TO_CHAR (x) || ' a '
     || ',       table_' || TO_CHAR (y) || ' b '
     || 'WHERE   a.col_1 = b.col1';Now let's make it really interesting. Say that instead of 2 tables, and 1 join condition, you''ll have n tables and n-1 join conditions, where n has to be computed at (actually a split second before) run-time. That is, if n=4, you might need to construct a static query with 4 tables and 3 join conditions, like this:
SELECT     a.col1, a.col2, b.col1, b.col7
FROM     table_1     a
,     table_2 b
,     table_12 c
,     table_2 d
WHERE     a.col1 = b.col1
AND     a.col1 = c.col1
AND     a.col1 = d.col1;You can do that using dynamic SQL, too.
Post an example of the static query you need to build, and describe what parts of it are dynamic, and how you get the values for those parts, and someone will help you write the dynamic SQL.