complicated sql queries

Label:That day: SELECT * from T_news where DateDiff (Day,addtime,getdate ()) =0 Last three days: SELECT * from T_news where DateDiff (Day,addtime,getdate ()) Week: SELECT * from T_news WHERE (DATEPART (wk, addtime) = DATEPART (wk, GETDATE ())) and (DATEPART (yy, addtime) = DATEPART (yy, GET DATE ())) Note: You cannot use the DateDiff difference at this time as 7, because DateDiff only represents the number of intervals Month: SELECT * from T_news WHERE (DATEPART (yy, addtime) = DATEPART (yy, GE

Because a small feature of recent projects requires a comparison of current data and history today. On the internet also looked for a long time, many are to achieve within one months, all the data in a year, last night suddenly found the following implementation method, in SQL Server2008 tried, it is I want results. Therefore wrote an essay, if later still need to be able to find, in addition also hope can help the people who need.SELECT * from the hi

Have you ever queried for the information you need? Sub-Select, also known as subqueries, may be exactly what you are looking for. This feature of SQL allows you to query in a set of results, creatively qualify the result group, or relate the result to an unrelated query in a single call to the database. In this article I will give examples of several sub selections and discuss when to use them. Search in a result group The idea of a sub-selection i

SQL Server queries all users who have purchased products in a certain period of time, and SQL server has bought The goods table is as follows: Name time productA 13:23:00 WFEYB 15:23:00; 34 ASGA 13:47:20 SGHC 19:56:03 HRTC 14:00:00 XCCA ESFW Select distinct oo. name FROM (SELECT name, DATE_FORMAT (time, '% h: % m') AS ti FROM goods) as oo where ti BETWEEN '12:

SQL Server queries all Sundays within a period of time, and SQL Sunday /* Query all Sundays within a period of time @ startdate start date @ enddate end date */declare @ startDate datetimedeclare @ endDate datetimedeclare @ week varchar (20) set @ startDate = '000000' set @ endDate = '000000' while @ startDate Copyright Disclaimer: This article is an origina

Select column_id, column_name, parent_id, (select column_name from [sort] Where column_id = A. parent_id) parent_name,(Select parent_id from [sort] Where column_id = A. parent_id) fathers_id,(Select column_name from [sort] Where column_id = (select parent_id from [sort] Where column_id = A. parent_id) father_nameFrom [sort] A where column_depth = 3 order by father_name DESC, parent_name DESC, column_name DESC Compared with SQL statements of niub,

In general Server databases operate in a single thread when performing query jobs. SQL Server provides the parallel query function to cope with large-volume query tasks. The advantage of parallel query is that it can process query jobs through multiple threads, thus improving the query efficiency. SQLThe server database provides the parallel query function for database servers with multiple CPUs to optimize the performance of query jobs. That is to s

The advantage of parallel query is that it can process query jobs through multiple threads, thus improving the query efficiency. The SQL Server database provides the parallel query function for database servers with multiple CPUs to optimize the performance of query jobs. That is to say, as long as the database server has multiple CPUs, the database system can use multiple operating system processes to execute query operations in parallel to accelerat

The advantage of parallel query is that it can process query jobs through multiple threads, thus improving the query efficiency. The SQL Server database provides the parallel query function for database servers with multiple CPUs to optimize the performance of query jobs. That is to say, as long as the database server has multiple CPUs, the database system can use multiple operating system processes to execute query operations in parallel to accelerat

Tags: underlying data different conditions SQL expression nbsp from table BlurGroup queriesSelect query information from table nameWhere conditionGroup By column (multiple, separated)Order by Sort method(Query information if the column name and aggregate function appear at the same time, either in an aggregate function or in a group query) Having conditional grouping filter (usually with group by, position behind) Where: A row that is used to filter t

This article from: http://www.cnblogs.com/bluedoctor/archive/2011/08/10/2133983.html In general, our ORM framework usesSingle TableOrViewMap to oneEntity classSometimes stored procedures are mapped to object classes. If you do not want to write the stored procedures, how can these complex SQL queries be mapped to object classes? In fact, whether it is a single table, view, or stored procedure,

When a query is made using an SQL statement, the result of the query is stored in a temporary file with a suffix named tmp. When the query, the file holds the results of the query, when the query is closed, the temporary file will be automatically deleted, so in our query, it is not feel the existence of the file. Where does the TMP file exist For Windows systems, there is a system environment variable that can be passed Right-click My Computer--Pr

Original: Using SQL Profiler to handle expensive queriesWhen the performance of SQL Server becomes worse, the following two things are most likely to occur: First, some queries produce a lot of pressure on system resources. These queries affect the performance of the entire system because the server is not abl

When the performance of SQL Server becomes worse, the following two things are most likely to occur: First, some queries produce a lot of pressure on system resources. These queries affect the performance of the entire system because the server is not able to serve other SQL

Label:Many people know about SQL injection, and they know that SQL parameterized queries can prevent SQL injection and why it is not known by many to prevent injection . This article is mainly about this question, perhaps you have seen this piece of content in some articles, of course, look at the same. First: We want

Many people know about SQL injection, and they know that SQL parameterized queries can prevent SQL injection and why it is not known by many to prevent injection .This article is mainly about this question, perhaps you have seen this piece of content in some articles, of course, look at the same.First: We want to under

server is not exactly the same as the server environment in which it is actually applied. As the resource requirements evolve, SQL Server automatically adjusts itself. If you have questions about this, you can run the same query repeatedly on a heavily loaded server, and in most cases, the time used to execute the query is different. Of course, the gap is not big, but the change is enough to make performance adjustment more difficult than it should

non-leaf nodes other than nodes, at least the M/2 son is included to ensure the minimum utilization of the end point. Its minimum search performance is:Among them, M is the number of non-leaf nodes set, n is the total number of keywords, so the performance of B-tree is always equivalent to binary lookup (independent of M-value), that is, the problem of no B-tree balance, due to the limitations of M/2, when inserting nodes, if the node is full, the node needs to be divided into two each M/2 When

: set the virtual memory size to at least three times the physical memory installed on the computer. Configure the SQL Server max server memory Server configuration option to 1.5 times the physical memory (half the virtual memory size ).　　7. Increase the number of server CPUs. However, you must understand that resources such as memory are more required for concurrent processing of serial processing. Whether to use parallelism or serial travel is autom

Reprinted from: http://www.cnblogs.com/LoveJenny/archive/2013/01/15/2860553.htmlMany people know about SQL injection, and they know that SQL parameterized queries can prevent SQL injection and why it is not known by many to prevent injection .This article is mainly about this question, perhaps you have seen this piece