inner join vs where clause performance sql server

times, physical read 0 times, read 0 times, LOB logic read 0 times, lob physical read 0 times, lob read 0 times.Table ' Verifyprocess '. Scan Count 9, logical read 3,136 times, physical read 0 times, read 0 times, LOB logic read 0 times, lob physical read 0 times, lob read 0 times. The performance of this example looks like the total time overhead difference is not obvious, because the number of connected tables is small, and if the number of tables

somecolumn in (SELECT lookupcolumn from dbo. smallertable) Select Bigtable.id, somecolumn from BigTable INNER JOIN (SELECT DISTINCT lookupcolumn FROM dbo. Smallertable) as s = dbo. Bigtable.somecolumn Finally the query cost and the above is not the same, at this time the query performance cost is the same, I believe here we should be very clear. We can derive

Cross Jointable2Select * fromTable1,table2--The following three statements have the same effectSelect * fromTable1 A,table2 bwhereb.ID=a.idSelect * fromTable1 A Cross JoinTable2 bwhereb.ID=a.idSelect * fromTable1 AInner JoinTable2 b onb.ID=a.ID2 Cross Apply,outer apply(Cross Apply,outer apply is new in SQL Server 2005)There is a cross join in

that inner join is not based on who, it only shows records that match the criteria.--------------------------------------------Note:The left JOIN operation is used to combine records from the source table in any from clause. Use the left JOIN operation to create an outer

if there are no corresponding values. SELECT * from dbo. Student a left JOIN dbo. Score B on A.sno=b.sno 　　 INNER JOIN Display Intersection SELECT * from dbo. Student a INNER JOIN dbo. Score B on A.sno=b.sno 　　 Right join all d

Reproduced in: http://www.2cto.com/database/201206/137067.html Comparison of SQL Server left Join,right join and inner join today to look at the database left join,Right

tables using the equivalent condition query.ANSI SQL-92 notation* FROMsales.orders as so = So.orderidANSI SQL-89 notation*= So.orderidAlthough both of these can be written to meet the requirements, the basic SQL Server 2012 Tutorial strongly recommends using ANSI SQL-92

From: http://www.williamlong.info/info/archives/50.html In a formal database environment, we often encounter this situation: the required data is not stored in the same data table. At this time, you need to use join. Of course, how to combine the data of different databases depends on how you use it. There are four different Join methods, in this article, we will introduce you to

thirdtable s on s.col1 = F.col1 G O We get the result is 5 2, why the use of the inner join means that the equivalent condition is not to return a 2, in fact, we can summarize as follows: Conclusion: The reason for using an inner join to return more data than the actual table is that the result set returned by

=b.statuscode and that is, there is a where condition control, and on can be followed by multiple conditions,the query results are the same as the first one.3. Right Join,right outer JOINRight join is called to connect, the right outer join is called an outer join, in fact is a kind of,The back on, can only be associat

of course join how to combine the data of different database, also depends on how you use it, there are four different ways of join, in this article we will introduce you Inner join and Outer join and its application. In a formalized database environment, we often encounter

(1) Cross join is what we call the Cartesian product. Query the number of records that satisfy both tables, A (3 Records), B (9 Records), A*b (27 records).For example: An employee table (hr.employees) and a freight company (sales.shippers) table make a cross-connection.1 SELECT * FROM hr.employees;2 select * from Sales.shippers;After the cross-connect, 27 records are found.1 Select A.empid,b.shipperid2 from hr.employees a cross

the same as that in the previous example! 4: Inner join or join; It is the record that the returned field ID exists in both the table votemaster and voter.5: Cross join (full join) with no where Condition A cross join without a w

without the where ConditionA cross join without a where clause will generate the Cartesian product of the table involved in the join. The number of rows in the first table multiplied by the number of rows in the second table is equal to the size of the Cartesian result set. (Table 1 and Table 2 generate 6*3 = 18 Records)Equivalent to select VM. ID, VM. votetitle

upper left and right connections) 2. Internal Connection1. Concept: inner join is a join that uses a comparison operator to compare the values of the columns to be joined. 2. Inner join: Join or

condition: SELECT statements with ON conditions are constraints for filtering the intermediate table. In a single table query without an ON clause, it is a restriction ON the return records of physical tables or intermediate query results. In a two-table or multi-table join, the join is restricted to the final result returned from the intermediate table.It can b

In-depth understanding of four SQL connections-left outer join, right outer join, inner join, and full link bitsCN.com 1. INNER JOIN(Typical join