Pass an array to bind variables - oracle

Question

I have a table that contains queries, for example:
select text from queries;
TEXT
1 select item from items where item_no between :low_item_no and :high_item_no and description <> :irellevant
The queries already contains the place holders for the bind variables.
The values themselves exists in variables table:
select * from vars;
ID NAME VALUE
1 1 low_item_no 100
2 2 high_item_no 300
3 3 irellevant_desc old
I have a package that takes the query and execute it with
execute immediate statement
but how do I bind those variables?
I don't know how much variables I have in such query, it's not static.
I wish to have a way to do something like that:
Execute immedaite my_query_str using v_array_of_vars;
Until now I don't know of a way to do something like that, only with list of variables for example:
Execute immedaite my_query_str using v_1, v_2, v_3;
Thanks!

Answer 1

I don't think you can do this with execute immediate as too much is unknown at compile time, so you'll have to use the dbms_sql package instead.
Here's a quick demo that gets the query and variables based on a common query ID. This assumes that the values in vars.name actually match the bind variable names in queries.text, and I haven't included any checks or error handling for that or other potential issues, or dealt with multiple select-list items or data types - just the basics:
declare
my_query_str queries.text%type;
my_cursor pls_integer;
my_result pls_integer;
my_col_descs dbms_sql.desc_tab2;
my_num_cols pls_integer;
my_item items.item%type;
begin
select text into my_query_str from queries where query_id = 42;
dbms_output.put_line(my_query_str);
-- open cursor
my_cursor := dbms_sql.open_cursor;
-- parse this query
dbms_sql.parse(my_cursor, my_query_str, dbms_sql.native);
-- bind all variables by name; assumes bind variables match vars.name
for r in (select name, value from vars where query_id = 42) loop
dbms_output.put_line('Binding ' || r.name || ' || with <' || r.value ||'>');
dbms_sql.bind_variable(my_cursor, r.name, r.value);
end loop;
my_result := dbms_sql.execute(my_cursor);
dbms_output.put_line('execute got: ' || my_result);
dbms_sql.describe_columns2(my_cursor, my_num_cols, my_col_descs);
dbms_sql.define_column(my_cursor, 1, my_item, 30); -- whatever size matches 'item'
-- fetch and do something with the results
while true loop
my_result := dbms_sql.fetch_rows(my_cursor);
if my_result <= 0 then
exit;
end if;
dbms_sql.column_value(my_cursor, 1, my_item);
dbms_output.put_line('Got item: ' || my_item);
end loop;
dbms_sql.close_cursor(my_cursor);
end;
/
You don't seem to really need an array; but if you wanted to you could create and populate an associative array as name/value pairs and then use that fir the binds.
This is just a starting point; you may have to deal with an unknown number and/or types of columns being returned, though if that's the case processing them meaningfully will be a challenge. Perhaps you need to return the result of the query as a ref cursor, which is even simpler; demo using the SQL*Plus variable and print commands:
var rc refcursor;
declare
my_query_str queries.text%type;
my_cursor pls_integer;
my_result pls_integer;
begin
select text into my_query_str from queries where query_id = 42;
dbms_output.put_line(my_query_str);
-- open cursor
my_cursor := dbms_sql.open_cursor;
-- parse this query
dbms_sql.parse(my_cursor, my_query_str, dbms_sql.native);
-- bind all variables by name; assumes bind variables match vars.name
for r in (select name, value from vars where query_id = 42) loop
dbms_output.put_line('Binding ' || r.name || ' || with <' || r.value ||'>');
dbms_sql.bind_variable(my_cursor, r.name, r.value);
end loop;
my_result := dbms_sql.execute(my_cursor);
dbms_output.put_line('execute got: ' || my_result);
:rc := dbms_sql.to_refcursor(my_cursor);
end;
/
print rc
Notice you don't close the cursor inside the PL/SQL block in this scenario.
You could also convert to a ref cursor and then fetch from that within your procedure - there's a bulk-collect example in the docs - but again you'd need to know the number and types of the select-list items to do that.