If none of the lines on the right-hand side fulfils the join_cond condition, no line is created in the resulting set. Resulting set for outer join The outer join basically creates the same resulting set as the inner join, with the difference that at least one line is created in the ...
查询SQL如下: SELECT COUNT(*) FROM pq_test; EXPLAIN查询语句 不使用并行查询的执行情况 通过EXPLAIN语句查看不使用并行查询的执行情况。 查询语句如下: 查询结果如下: *** 1. row *** Id: 1 Select_type: SIMPLE Table: pq_test Partitions: NULL Type: index Possible_keys: NULL Key: PRIMARY Key_len...
<sql_operation type="statement">CREATE TABLE [tempdb].[dbo]. [Q_[TEMP_ID_259]]_ [PARTITION_ID]]]([dist_date] DATE) WITH (DISTRIBUTION = HASH([dist_date]),) </sql_operation> RemoteOnOperation <DestinationCatalog>设置用户帐户 :目标目录。<DestinationSchema>设置用户帐户 :DestinationCatalog...
Oracle Database generates an internal SQL statement, which in turn generates a recursive call. In short, recursive calls are basically SQL performed on behalf of your SQL. So, if you had to parse the query, for example, you might have had to run some other queries to get ...
The following example illustrates an RLS SecureScan node. EXPLAINSELECTD.cintFROMfact_tbl FINNERJOINdim_tbl DONF.k_dim=D.kWHEREF.k_dim/10>0; QUERY PLAN---XN HashJoinDS_DIST_ALL_NONE (cost=0.08..0.25rows=1width=4) Hash Cond: ("outer".k_dim="inner"."k")->*XN**RLS SecureScan ...
以下面的sql为例(sakila样例数据库中的address city country连接查询) select address.address, city.city, country.country from address inner join city on address.city_id = city.city_id inner join country on city.country_id = country.country_id; ...
above. As an analogy to the coding world, you can look at the concept of an inner join as very similar to a nested loop. MySQL chooses the table it thinks will be best to start the journey with (the outer "loop") and then touches the next table using the values from the outer "...
This is an internal optimizer object with no user significance. /* select#N*/select_stmt TheSELECTis associated with the row in non-extendedEXPLAINoutput that has anidvalue ofN. outer_tablessemi join (inner_tables) A semijoin operation.inner_tablesshows the tables that were not pulled out. ...
with 48 commentsFrom Stack Overflow: Can anyone give me a good example of when CROSS APPLY makes a difference in those cases where INNER JOIN will work as well? This is of course SQL Server. A quick reminder on the terms. INNER JOIN is the most used construct in SQL: it joins two ...
As an example, we’ll use data from the Sakila Sample Database and a query that lists the total amount each staff member has rung up in August 2005. The query is straight forward: SELECT first_name, last_name, SUM(amount) AS total FROM staff INNER JOIN payment ON staff.staff_id = ...