oracle - oracle: INSERT where a=b

Question

I need to insert values into table only when condition is true.

I try to do smth like this:

select (case when a = b  
 then insert into tbl values (1, 1) end) 
            from dual;

But it doesnt work:(

Answer 1

このようにしてください：-

INSERT INTO tbl 
  (column1, column2) 
VALUES( 
  (SELECT column1 FROM table1 WHERE a=b), 
  (SELECT column2 FROM table2 WHERE a=b)
)

更新しました：

INSERT INTO tbl 
  (column1, column2) 
SELECT column1, column2 FROM dual WHERE a=b