update with subquery sql server

Label:/* Update--1 using an update with the associated subquery . Create a test table Create TABLE Table1 ( a varchar (ten), B varchar (ten), C varchar (ten), CONSTRAINT [pk_ Table1] PRIMARY KEY CLUSTERED ( a ASC ) ) on [PRIMARY] create TABLE table2 ( a varchar (ten), C varchar (ten), CONSTRAINT [pk_table2] PRIMARY KEY Clustered ( a ASC )

Technical preparationThe database version is SQL Server2008R2 and is analyzed using Microsoft's simpler case Library (Northwind.1. Independent subqueryThe so-called independent subquery method means that the subquery is irrelevant to the primary query. The advantage of this method is that the subquery does not depe

Original: SQL Server Tuning Series Basics (subquery operations Summary)ObjectiveIn the previous articles, we introduced a series of descriptions of operators and the optimization methods and techniques for each operator. This includes a series of our common operators, including how to view execution plans, how several datasets are commonly used, how to join opera

. Orderid,o1. Freightfrom Orders o1where O1. Freight>( SELECT AVG. O2. Freight) from Orders O2)The goal of SQL execution is to query orders that have more than the average shipping charge in the order.The clause that extracts the average freight here is a completely independent subquery that executes independently of the main query. At the same time here we take advantage of a scalar computation (AVG) s

. Orderid,o1. Freightfrom Orders o1where O1. Freight>( SELECT AVG (O2). Freight) from Orders O2)The goal of SQL execution is to query orders that have more than the average shipping charge in the order.The clause that extracts the average freight here is a completely independent subquery that executes independently of the main query. At the same time here we take advantage of a scalar computation (AVG)

Label:--Paging data----row_number () is called window-opening function, can be paged operation Select Row_number () over (order by ID) as Num,*from gb_data----adds a sequential num value to each column to facilitate the use of the first few data. Select row_number () over (order by ID) as num,* from Gb_data where Num>5and num 10--This line of code is wrong, because the system does not recognize how much num is, why? -Because of the order of execution, the

Label:Source: Why not a subquery in SQL Server is not recommendedIn SQL Server, subqueries can be divided into correlated subqueries and unrelated subqueries, but not-in clauses are common for unrelated subqueries, but the not-in clause leads to the following two types of pr

subquery (in)The Code is as follows:SelectTestID, stuID, testBase, testBeyond, testProFrom ScoreWhere stuID in (Select stuID from Student where stuName = 'kencery') 2) related subqueries(3) Notes for writing subqueries1) The subquery is wide in parentheses. If necessary, you need to take an alias for the table and use "as name.2. Table join \(1) A table link combines multiple tables into one table, but doe

Atitit. mysql oracle with as mode temporary table mode CTE statement, reduce the subquery structure mssql SQL server..., atitit. mysqlcte Atitit. Use of the CTE statement in the temporary table mode of mysql oracle with as mode to reduce the structural mssql SQL server of su

How to use SQL Server database nested subquery How to use SQL Server database nested subquery Many SQL Server programmers are confused abou

SQL Server in contrast to Oracle, if the subquery involved, then the corresponding table name, field must be named an alias to execute. There are two main types of situations: 1. Query SQL inside only a simple subquery does not contain grouping, sum wait Eg:elect * FROM (se

sets are called sub-queries. There are two types of sub-queries: One is to return only a single-valued subquery, at which point it can be used where a single value can be used, when a subquery can be considered a function that has a return value; Another is a subquery that returns a column of values, at which point the s