下面看看原始SQL和增加DISTINCT后的差别: SQL> SET AUTOT TRACE SQL> SELECT T1.OBJECT_NAME, T1.OBJECT_TYPE,T2.TABLESPACE_NAME 2 FROM T1, T2 WHERE T1.OBJECT_NAME = T2.SEGMENT_NAMEAND T1.OBJECT_NAME IN 3 (SELECT INDEX_NAME FROM T3 WHERE T3.TABLESPACE_NAME= T2.TABLESPACE_NAME); 311 rows...
同时,还将解释说明Distinct在PL/SQL中的作用和效果,并提供一些实际案例分析以及常见使用场景和经验分享。 1.3 目的 本文的目标是帮助读者全面了解PL/SQL Distinct的用法,包括基本概念、语法和用法,以及其在查询中的应用示例。此外,我们也将解释说明Distinct在PL/SQL中的作用和效果,并提供一些性能优化注意事项和技巧。
【SQL】SQL中distinct的用法在表中，可能会包含重复值。这并不成问题，不过，有时您也许希望仅仅列出不...
mysql> Select player_id,distinct(task_id) from task; ERROR 1064 (42000): You havean error in your SQL syntax; check the manual that corresponds to your MySQLserver version for the right syntax to use near 'disti nct(task_id) from task' atline 1 现在把distinct放在开头 mysql> Select dis...
PL/SQL procedure successfully completed. 下面看看原始SQL和增加DISTINCT后的差别: SQL> SET AUTOT TRACE SQL> SELECT T1.OBJECT_NAME, T1.OBJECT_TYPE,T2.TABLESPACE_NAME 2 FROM T1, T2 WHERE T1.OBJECT_NAME = T2.SEGMENT_NAMEAND T1.OBJECT_NAME IN ...
The syntax for the DISTINCT clause in Oracle/PLSQL is: SELECT DISTINCT expressions FROM tables [WHERE conditions]; Parameters or Arguments expressions The columns or calculations that you wish to retrieve. tables The tables that you wish to retrieve records from. There must be at least one table...
SQL> SET AUTOT TRACE SQL> SELECT T1.OBJECT_NAME, T1.OBJECT_TYPE, T2.TABLESPACE_NAME 2 FROM T1, T2 3 WHERE T1.OBJECT_NAME = T2.SEGMENT_NAME 4 AND T1.OBJECT_NAME IN 5 ( 6 SELECT INDEX_NAME FROM T3 7 WHERE T3.TABLESPACE_NAME = T2.TABLESPACE_NAME ...
PL/SQLproceduresuccessfully completed. 仍然沿用上面例子中的结构,看看原始SQL和增加DISTINCT后的差别: SQL>SETAUTOT TRACE SQL>SELECTT1.OBJECT_NAME, T1.OBJECT_TYPE, T2.TABLESPACE_NAME 2FROMT1, T2 3WHERET1.OBJECT_NAME=T2.SEGMENT_NAME 4ANDT1.OBJECT_NAMEIN ...
PL/SQL procedure successfully completed. 2.建立测试环境: create table t as select * from all_objects; create index i_t_owner on t(owner) COMPRESS 1; --//alter table t modify owner not null;这步不需要。 --//分析略。 CREATE OR REPLACE FUNCTION distinct2varlist ...
GROUP BY 重复字段 HAVING COUNT(*) > 1); ``` 删除重复记录 删除重复记录可以使用以下 SQL 语句: ```sql DELETE 表 WHERE 重复字段 In (SELECT 重复字段 FROM 表 GROUP BY 重复字段 HAVING COUNT(*) ... 基于SQL语句的全样本数字化审计示例分析.pdf GROUP BY t.cl_desc ORDER BY t.cl_desc_...