无法在SQL查询APEX ORACLE中将绑定变量用作表名

Question

SELECT * FROM :TABLENAME 

is my query, and Apex isn't letting me run because the app doesn't know the table name. How can I dynamically query using variable as the table name.

Answer 1

Here's how:

• create a classic report using a dummy SELECT statement, such as select * from dual
• create a text item on that page, let's call it P22_TABLE_NAME
• set its "Submit when enter pressed" property to "Yes"
• edit report's source and set the Type to PL/SQL Function Body returning SQL Query
• Function body should be return 'select * from ' || :P22_TABLE_NAME; return 'select * from ' || :P22_TABLE_NAME;
• set "Use generic column names" property to "Yes", because you're using different table names, and all of them (most probably) have different columns
• run the page; as you put different table names into the P22_TABLE_NAME item and press the Enter key, report contents should change

Answer 2

You should know what tables the form might need to query. If you have an application item called TABLE_NAME , you can union the results together and pick out the right table like this:

select col1, col2, col3 from tablex where :TABLE_NAME = 'TABLEX'
union all
select col1, col2, col3 from tabley where :TABLE_NAME = 'TABLEY'
union all
select col1, col2, col3 from tablez where :TABLE_NAME = 'TABLEZ'

The benefit of this approach is that the query will be checked for correct syntax and that the tables have the right columns; and this solution is immune from SQL injection attacks.

The downside is that if a new table is added, you have to modify the query. But if you're creating tables on the fly like this then you should consider revising your strategy anyway.