Question

I’m writing SQL (for Oracle) like:

 INSERT INTO Schema1.tableA SELECT * FROM Schema2.tableA; 

where Schema1.tableA and Schema2.tableA have the same columns. However, it seems like this is unsafe, since the order of the columns coming back in the SELECT is undefined. What I should be doing is:

 INSERT INTO Schema1.tableA (col1, col2, ... colN)  SELECT (col1, col2, ... colN) FROM Schema2.tableA; 

I’m doing this for lots of tables using some scripts, so what I’d like to do is write something like:

 INSERT INTO Schema1.tableA (foo(Schema1.tableA))  SELECT (foo(Schema1.tableA)) FROM Schema2.tableA; 

Where foo is some nifty magic that extracts the column names from table one and packages them in the appropriate syntax. Thoughts?

Answer 1

This PL/SQL should do it:

declare     l_cols long;     l_sql  long; begin     for r in (select column_name from all_tab_columns               where  table_name = 'TABLEA'               and    owner = 'SCHEMA1'              )     loop        l_cols := l_cols || ',' || r.column_name;     end loop;      -- Remove leading comma     l_cols := substr(l_cols, 2);      l_sql := 'insert into schema1.tableA (' || l_cols || ') select '               || l_cols || ' from schema2.tableA';      execute immediate l_sql;  end; /