select /*+ monitor */ * from T1 where exists(select 1 from T2 where T1.sql_id = T2.sql_id) ; select /*+ monitor */ * from T1 where T1.sql_id in (select T2.sql_id from T2) ;SQL>select sql_id, sql_text from v$sqlwheresql_text like'%T2.sql_id%'SQL_ID SQL_TEXT ---...
8i CBO下in和exists比较ora8@ORACLE8I> select count(1) from big_table b where b.object_id in (select object_id from small_table s); Execution Plan --- 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=52 Card=1 Bytes=16) 1 0 SORT (AGGREGATE) 2 1 NESTED LOOPS (Cost=52 Card=3136 Bytes=501...
| 0 | SELECT STATEMENT | | 217K | 15M| 1375 (2) | 00:00:17 ||* 1 | HASH JOIN | | 217K | 15M| 1375 (2) | 00:00:17 || 2 | SORT UNIQUE | | 217K | 848K| 126 (1) | 00:00:02 || 3 | INDEX FAST FULL SCAN | IDX2_B | 217K | 848K| 126 (1) | 00:00:...
AI代码解释 --SQL1:select/*+ monitor */SQL_ID,SQL_PLAN_HASH_VALUE,SQL_PLAN_LINE_ID,count(*)fromT1whereT1.sql_idin(selectT2.sql_idfromT2)group bySQL_ID,SQL_PLAN_HASH_VALUE,SQL_PLAN_LINE_IDorder by1;--SQL2:select/*+ monitor */SQL_ID,SQL_PLAN_HASH_VALUE,SQL_PLAN_LINE_ID,coun...
On another note, I read that there are plans, or at least a feature request, to support something along the lines of T-SQL's @@ERROR, where in you can check if an error occurred exactly after a statement. Example: INSERT INTO table (col1, col2, col3) VALUES (val1, val2, val...
| 0 | SELECT STATEMENT | | 7 | 168 | 3 (0)| 00:00:01 | | 1 | NESTED LOOPS | | 7 | 168 | 3 (0)| 00:00:01 | | 2 | TABLE ACCESS FULL| EMP1 | 7 | 140 | 3 (0)| 00:00:01 | |* 3 | INDEX UNIQUE SCAN| PK_EMP | 1 | 4 | 0 (0)| 00:00:01 | ...
A condition that evaluates to UNKNOWN acts almost like FALSE.For example, a SELECT statement with a condition in the WHERE clausethat evaluates toUNKNOWN returns no rows. However, a condition evaluatingto UNKNOWN differs from FALSE in that further operations onan UNKNOWN condition evaluation will eva...
Is a restricted SELECT statement. The COMPUTE clause and the INTO keyword are not allowed. For more information, see the information about subqueries inSELECT (Transact-SQL). Result Types Boolean Result Values Returns TRUE if a subquery contains any rows. ...
Is a restricted SELECT statement. The INTO keyword is not allowed. For more information, see the information about subqueries inSELECT (Transact-SQL). Result Types Boolean Result Values Returns TRUE if a subquery contains any rows. Examples ...
The common response was to count the records and then to perform an IF statement. I agree with Naveen that this is an inefficient method. I think that Tom was looking for something like the following pseudo-code, which at the time works for me (I haven't tried in production yet): ...