how to optimize sql query with multiple joins

Multiple SQL tables query and computing statistics code based on ACCESS and ASP, accesssql Recently, I am writing a few management systems about "Project-Subitem-Task", saying that the system is a bit exaggerated. It is basically a multi-Table query call and database operations of insert and update, the

Recently, the company is working on the Wuhan public transport information management system. The most painful thing for such management projects is the addition, modification, and query of forms. Add or modify Article As mentioned in, the reflection mechanism can be used to do nothing. Code . See Automatic Data Binding and modification in the ORM framework The above only solves the problem of adding, modifying, and displaying the list. However,

Label:Reprint Http://hi.baidu.com/my_favourate/item/3716b0cbe125f312505058ebSQL query multiple non-repeating record values brief analysis 2008-02-28 11:36 below test under Oracle 10gBecause of the design needs, need to query the record value of the same kind of problem, presumably we have encountered, so immediately Google, found that this kind of problem is quit

Label:1. Query the MySQL statement as needed, return three required parameters, not a dataset 2. Write the function as follows: public static void Getparas (string condition 1, out string return value 1, out string return value 2, out string return value 3){The return value is 1= string. Empty;The return value is 2= string. Empty;The return value is 3= string. Empty; String strSQL = String. Format ("SELECT * from table where field 1= ' {0} ' limit 1"

SQL Server database paging query has always been a short board of SQL Server, so I have nothing to worry about. I have come up with several methods, for example, table ARTICLE, field ID, YEAR... (others omitted). There are 53210 million pieces of data (the customer's actual data is not big), 30 pieces of data are queried by PAGE, 1,500th pages are queried (that i

, previous system design vulnerabilities have resulted in repeated insertion of multiple pieces of data.:For example:Kung Fu, Stephen ChowKung Fu, Huang shengyiKung Fu, Stephen ChowAs a result, Zhou xingchi made two moves in our database. Could you please design an SQL statement to help me quickly find out the redundant items and movie IDs. Keep records with the smallest id

Tags: data SP problem BS database server SQL as installationWhen SQL Server accesses a database table in Oracle remotely:The remote syntax is typically: SELECT * from OpenQuery (Oracle linked server name, ' query statement ')Eg:select * from OPENQUERY (QTX, ' select * from student ')In some cases, only the first piece of data is returned from the student table.WO

Problem Description:Neither in SQL 2000, nor in SQL 2005, does the aggregate function of the string be provided,Therefore, when we are dealing with the following requirements, it will be more troublesome:There are table TB, as follows:ID value----- ------1 AA1 BB2 AAA2 BBB2 CCCNeed to get results:ID values------ -----------1 AA,BB2 AAA,BBB,CCCThat is, the group by ID, the sum of the value (string addition)1

For example, there is a personnel table (table name: peosons) Select P1. * from persons P1, persons P2 where p1.id The above results can be achieved. Several SQL statements used to delete Repeated Records 1. Use the rowid Method 2. Use the group by Method 3. Use the distinct method 1. Rowid Method The statement is as follows: Query data: Select * From Table1 A where rowid! = (Select max (rowid)

When you combine data across multiple tables, it is sometimes difficult to figure out which SQL syntax to use. I'll be here to illustrate the common way to combine queries from multiple tables into a single declaration. The sample query in this article conforms to the SQL92 ISO standard. Not all database manufacturers

SQL Server database paging query has always been a short board of SQL Server, so I have nothing to worry about. I have come up with several methods, for example, table ARTICLE, field ID, YEAR... (others omitted). There are 53210 million pieces of data (the customer's actual data is not big), 30 pieces of data are queried by PAGE, 1,500th pages are queried (that i

Tags: Dev SQL rom table data query data from where deviceSelect(SELECT COUNT (*) from DEVICE0 where status! = 0),(SELECT COUNT (*) from Device1 where status! = 0),(SELECT COUNT (*) from Device2 where status! = 0),(SELECT COUNT (*) from device3 where status! = 0),(SELECT COUNT (*) from Device4 where status! = 0),(SELECT COUNT (*) from device5 where status! = 0),(SELECT COUNT (*) from Device6 where status! =

What if we want to insert multiple lines of records? You might want to run the INSERT statement multiple times, just like the following PHP code example:INSERT into Tbl_name (col1,col2) VALUES (.);What if we want to insert multiple lines of records? You might want to run the INSERT statement multiple times, just like t

SQL Multiple primary key tables, when the inserted data is duplicated, are prompted to violate the primary KEY constraint that cannot be inserted by the error. So, how do I find duplicate values for the inserted data? Workaround: Use Group bySuppose there is a table #a , there are saleid,vendorid,comid,price,saleprice,quantity and other fields. The primary key is: Saleid,vendorid,comid three of them. Assu

The results of the query before processing are as follows:By using the definition of SQL variablesDECLARE @Scope varchar( +)DECLARE @Num int SET @Scope="'SET @Num = 1 SELECT @Scope=@Scope+Convert(varchar(8),@Num)+','+Descscope+Descoper+';',@Num = @Num+1 fromFuel_contractqualitynewWhereContractid='012009000100'SELECTContractid,@Scope fromFuel_contractqualitynewWhereContractid='012009000100' GROUP byCo

Whether int or varchar is used, it is hard to cope with multiple Status queries. For example, in general thinking, The Enum settings for CustomerStatus are as follows: Copy codeThe Code is as follows: [Serializable] Public enum CustomerStatus { New = 0, Active = 1, Overdue = 2, Sushortded = 3, Closing = 4, Closed = 5 } The Status value is stored in the database as an int.What should I do if I want to search for a Customer in the Active, Overdue, and s

(); } #endregion #regionIEnumerable MembersIEnumerator Ienumerable.getenumerator () {return((IEnumerable) results). GetEnumerator (); } #endregion #regionIfunctionresult Members Public Objectreturnvalue {Get{returnreturnvalue;} } #endregion #regionIDisposable Members Public voidDispose () {}#endregion } View Code Detailed Visibility HTTP://SOCIAL.MSDN.MICROSOFT.COM/FORUMS/EN/LINQPROJECTGENERAL/THREAD/F403E047-E38C-45AB-9155-DBF83

// Name field corresponding to textbox1// The password field corresponding to textbox2Using system;Using system. Collections. Generic;Using system. componentmodel;Using system. Data;Using system. drawing;Using system. text;Using system. Windows. forms;Using system. Data. sqlclient; Namespace findrow{Public partial class form1: Form{String SQL;Public form1 (){Initializecomponent ();} Private void button#click (Object sender, eventargs E){If (textbox1.t

Whether int or varchar is used, it is hard to cope with multiple Status queries. For example, in general thinking, The Enum settings for CustomerStatus are as follows:Copy codeThe Code is as follows:[Serializable]Public enum CustomerStatus{New = 0,Active = 1,Overdue = 2,Sushortded = 3,Closing = 4,Closed = 5} The Status value is stored in the database as an int.What should I do if I want to search for a Customer in the Active, Overdue, and suincluded s

Recently wrote a few about the "project-subitem-task" management system, said the system is still a little exaggerated, basically is a multi-table query call and INSERT, update database operation, but there are a lot of computational and statistical problems, making SQL appear complex. Therefore, it is necessary in a phase after the completion of the task, do a summary, some of the test process of