实际上和下面的语句求出的值是一样的 select COUNT(DISTINCT T2.B1) from T1 inner join T2 on T1.A1 = T2.A1; 3、从上面的分析可以看出你使用【left join】的目的只有一个就是得到【T1】表全部数据的【COUNT(DISTINCT T1.A1)】,所以试试改成下面的sql是否性能能够快些...
LEFT JOIN vs. LEFT OUTER JOIN in SQL Server As per the documentation:FROM (Transact-SQL): <join_type>::=[ {INNER|{ {LEFT|RIGHT|FULL} [OUTER] } } [<join_hint>] ]JOIN The keywordOUTERis marked as optional (enclosed in square brackets). In this specific case, whether you specifyOUTE...
As per the documentation:FROM (Transact-SQL): <join_type> ::= [ { INNER | { { LEFT | RIGHT | FULL } [ OUTER ] } } [ <join_hint> ] ] JOIN 1. 2. 3. The keywordOUTERis marked as optional (enclosed in square brackets). In this specific case, whether you specifyOUTERor not ...
Applies to: SQL ServerBy default, the Query and View Designer creates an inner join between tables. Inner joins eliminate the rows that do not match with a row from the other table. Outer joins, however, return all rows from at least one of the tables or views mentioned in the FROM cla...
当把条件加入到join子句时,SQL Server、Informix会返回外连接表的全部行,然后使用指定的条件返回第二个表的行。如果将条件放到where子句中,SQL Server将会首先进行连接操作,然后使用where子句对连接后的行进行筛选。下面的两个查询展示了条件放置位子对执行结果的影响:...
sql-server t-sql join Share Improve this question Follow edited Oct 26, 2015 at 14:47 user1822 asked Oct 26, 2015 at 14:14 Alen Švigelj 1133 bronze badges Add a comment 1 Answer Sorted by: 1 The problem is in your WHERE clause. This piece of code in your WHERE clause...
Learn about LEFT and RIGHT OUTER JOIN. Natively compiled T-SQL modules support LEFT and RIGHT OUTER JOIN in SQL Server.
You execute a query against sys.dm_exec_query_stats and sys.dm_exec_procedure_stats by using an outer join in Microsoft SQL Server 2012. You mismatch the join criteria like joining sql_handle to plan_handle....
In SQL Server join syntax we can use LEFT JOIN or LEFT OUTER JOIN and query result with each of above join not difference. this is a question for me that which are more useful.sql-server sql-server-2008 sql-server-2008-r2 t-sql join...
Join Two Database Tables in Catalog and Schema Use an ODBC connection to import product data from an outer join between two Microsoft® SQL Server® database tables into MATLAB®. Specify the database catalog and schema where the tables are stored. ...