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...
select staff_name from staff_member where staff_id in (select staff_id from staff_member minus select staff_id from staff_func where func_id like '81%'); in 与 "=" 的区别 select name from student where name in ('zhang','wang','li','zhao'); 与 select name from student where nam...
| 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:...
用SCOTT/TIGER登录。 创建小表:‘ CREATE TABLE EMP1 AS WITH TEMP_EMP AS (SELECT ROWNUM RN, E.* FROM EMP E) SELECT * FROM TEMP_EMP WHERE RN BETWEEN 4 AND 10; 1. 开启AUTOTRACE: SQL> SET AUTOTRACE ON 1. 查看IN的执行计划: SQL> SELECT EMPNO, ENAME FROM EMP1 WHERE EMPNO IN (SELECT...
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 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 ...
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. ...
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): ...
A restricted SELECT statement. Result Types bit Return Value Returns TRUE if a subquery contains any rows. Example The following example finds all orders in the Orders table, with "Washington" as the Shipping Region, for each employee listed in the Employees table. ...
SelectElement SelectFunctionReturnType SelectInsertSource SelectiveXmlIndexPromotedPath SelectScalarExpression SelectSetVariable SelectStarExpression SelectStatement SelectStatementSnippet SemanticFunctionType SemanticTableReference SendStatement SensitivityClassification SensitivityClassification.OptionType SensitivityCl...