注意观察上面的SQL语句,t1,t2表都被访问了2次,而且t1表2次访问都是同一条SQL语句(子查询),t2表也被访问了2次,但是2次的SQL结构基本一样,所以这里可以用with as优化该SQL WITH b AS (SELECT * FROM t1 WHERE id<100), a as (select * from t2 where id<100) SELECT a.sex, b.* FROM a inner ...
思路 就跟 这个博客一样的http://blog.csdn.net/robinson1988/article/details/10551467我靠 居然还个sb在乱评论 因为in里面有点复杂,不好用hint,我偷懒,难得去搞了,直接 用下面的sql 优化 with x as (SELECT /*+ materialize */ "VOUCHER".FID "ID" FROM T_GL_Voucher "VOUCHER" INNER JOIN T_GL_Vou...
一、hivesql中(注意:mysql不支持),with as语句的作用是相当于创建了一个中间表,加载到内存中,这样在后续的使用中极大的提高速度(不用建表,insert数据到中间表;加载内存,使用数据速度快)。 二、使用 WITH t1 AS ( SELECT * FROM carinfo ), t2 AS ( SELECT * FROM car_blacklist ) SELECT * FROM t1, ...
WITH <alias_name> AS (subquery_sql_statement) SELECT <column_name_list> FROM <alias>; 多个别名 WITH <alias_one> AS (subquery_sql_statement), <alias_two> AS (sql_statement_from_alias_one) SELECT <column_name_list> FROM <alias_one>, <alias_two> WHERE <join_condition>; 下面开始实战环...
Oracle在9i中引入了with语句。with语句用来给查询语句中的子查询命名,随后就可以在查询语句的其他地方引用这个名称。 格式如下: WITH <alias_name> AS (subquery_ sql statement) SELECT <column_name_list> FROM <alias>; 3.解决方案 WITH TMP_TABAS ...
1 语法：WITHsubquery_nameAS(the aggregation SQL statement)SELECT(query naming subquery_name);2 创建测试表tbl1、tbl2，往tbl1里插入2条数据，往tbl2里插入1000000条数据 3 此时我们单看一下全表扫描tbl2时的情况。通过下图，我们看到单对tbl2全表扫描时的逻辑读为6911 4 下面我们构造一个相关子查询，看看...
WITHsubquery_nameAS(the aggregationSQLstatement)SELECT(query naming subquery_name); With查询语句不是以select开始的,而是以“WITH”关键字开头。 可认为在真正进行查询之前预先构造了一个临时表TT,之后便可多次使用它做进一步的分析和处理 优点 使用SQL with 子句的优点, ...
I have a query which truncates and inserts data from the stored procedure table. However, I am not able to create stored procedure since I have;Withstatement afterINSERT INTOtable. The query is below. Can someone please help me? CREATEPROCEDURE[BC].[TestStoredProc]ASBEGINTRYsetnocountonsetxact...
can you add colour to a fields output in T-SQL? Can you change the value of yes or no instead of true or false use data type (BIT) ? Can you have a TRY CATCH in dynamic SQL? Can you Select From (another query)? Can you use a case statement as part of a left join Can't ...
'<statementname>' 陳述式需要陣列 <type> '<methodname>' 與其他跨繼承階層架構的同名成員產生衝突,所以應該宣告為 'Shadows' <type> '<typename>' 遮蔽基底類別中可覆寫的方法 '<type>' 只能繼承一次 <type> 參數不可以宣告為 'Optional' <type> 參數不可以宣告為 'ParamArray' <type1> '<membername>'...