tricky sql queries

Procedure Querylacklonorlattdcell (I_region_name varchar2, i_state varchar2) isbegin Select Region_name, state From gc3_td_site_history where 1 = 1 and region_name = decode (i_region_name, NULL, Region_name, i_ Region_name) and InStr (decode (i_state, NULL, State, i_state), state) > 0;end;If I_region_name is null, all region_name are queried; otherwise press I_region_name query.If i_state is null, all state is queried, and if I_state is "State1,state2", it is equivalent to

The number/frequency of SQL queries in ORACLE and the number of SQL queries in oracle In ORACLE Database Application optimization, the execution Frequency/frequency of an SQL statement is also frequently concerned, because the execution of an

This article will discuss the similarities and differences between simple nested queries and non-nested queries in SQL, through which you can better understand SQL statements. One day's work was to fix the bug of a project, and then we found that its SQL statements were extr

Tags: style blog color io os ar sp div c #regionImplementing fuzzy queries with parameter-based SQL statements (multi-criteria queries)StringBuilder SB=NewStringBuilder ("SELECT * FROM Books"); Liststring> listwheres =Newliststring>(); ListNewList(); if(TxtBookName.Text.Trim (). Length >0) {Listwheres.add ("bookname like @bkName"); Listparams.add (NewS

PrefaceMyBatis, as we all know, the semi-automatic ORM framework, originally called Ibatis, and later seemed to be the 10 Apache software fund hosting it to Goole Code, renamed the MyBatis, the function is more powerful than before. It's a relatively fully automatic, durable framework hibernate, more flexible and lightweight, which I still have a deep understanding of.One of the powerful features of MyBatis is the dynamic SQL capability, can save us a

table As a table example select E.emono,e.ename from (SELECT * from where deptno=30) E gave the table an alias E As a condition there are several situations Single-column: You can use =,>, A multiline column (collection) can be Single-row multi-column (object) is a row, like an object, what property has Multiline multiple columns: Multiple rows and columns are always used as tables from behind Single-row Example: SELECT * from emp where sal > (select

, therefore, is also called an inline view. When you use a query in the FROM clause, you must specify an alias for the subquery. 3, paging query1) Top N: First N records. Select Top 5 * from emp ORDER by HireDate Displays information from 5th to 9th persons (by Sal High and low) Select Top 5 from EMP where empno not in (select Top 4 empno from emp ORDER BY Sal Desc) Order by Sal Desc Identity: Indicates that the field is growing from "1", with "1" added e

For SQL queries in Hibernate, the query results are accepted as new objects. For hql queries Zookeeper package com. ucap. netcheck. dao. impl; import java. util. arrayList; import java. util. list; import org. hibernate. query; import org. hibernate. session; import org. hibernate. sessionFactory; import org. springframework. beans. factory. annotation. autowired

* from local table nbsp;--Update local table update B set B. column b=a. Column Bfrom openquery (srv_lnk, ' SELECT * from database. dbo. Table name ') as a inner Join local Table B on A. Column a=b. Column a--"Method 4" 2.3, Opendatasource/openrowsetselect * from OpenDataSource (' SQLOLEDB ', ' Data source=ip/servername; User id= login name; password= password '). Database name. dbo. Table name select * from OpenDataSource (' SQLOLEDB ', ' Date source=192.168.1.58;user id=sa; password=12345

In SQL queries, we usually use IN to query results based on the set of known IDs. The ID set is provided directly after the IN statement or a subquery is followed by the IN statement. In SQL queries, we usually use IN to query results based on the set of known IDs. The ID set is provided directly after the IN statement

); // Ps.settimestamp (2, tsdateend); New java.sql.Date (Tsdatestart.gettime ())); Ps.setdate (new java.sql.Date (Tsdateend.gettime ()));Refer to C #:The code is as followsString sql = "SELECT * from Lis_v_labtestsample WHERE patient_id=:P";Hlsaccess.commandtext = SQL;HlsAccess.Parameters.Clear ();HLSACCESS.PARAMETERS.ADD (":P", Oracle.DataAccess.Client.Oracle

can ensure that the database will faint. In addition, execution plans can be reused, and the simpler SQL statements are more likely to be reused. Complex SQL statements have to be re-parsed as long as one character changes, and then the bulk of the garbage is stuck in memory. It is conceivable how inefficient the database will be. 4. Staging intermediate results using temporary table An important way to si

that the database will faint.In addition, execution plans can be reused, and the simpler SQL statements are more likely to be reused. Complex SQL statements have to be re-parsed as long as one character changes, and then the bulk of the garbage is stuck in memory. It is conceivable how inefficient the database will be.4. Staging intermediate results using temporary tableAn important way to simplify

modified is found, the X lock on the resource being modified is required. SQL Server avoids deadlock problems with u locks. Because S-Lock and S-Lock are compatible, the U-Lock and S-lock are compatible to make the update lookup not affect the data lookup, and the U-Lock and U-Lock are not compatible, thus reducing the possibility of deadlock. Intent Lock (is IX IU): Intent Lock is more like an indicator than a lock. In

How to write better SQL queries: Ultimate Guide-Part 2: Ultimate SQL query In the previous article, we learned how to execute SQL queries and what to note when writing SQL query statements. Next, I will learn more about query met

SQL query beginner's Guide Reading Notes (2) Creating SQL queries, beginner's guide SQL PARTII: SQL Basics CHAPTER 4 Creating a Simple Query This section describes how to create an SQL statement: "Request/Translation/CleanUp/

Use non-dynamic SQL Server SQL statements to execute dynamic queries. This article mainly tells you about non-dynamic SQL ServerSQL statement execution of dynamic queries. In actual operations, I try to pass a series of values that define the boundary with commas in a stored

produce one or more candidate execution plans. Select the least expensive plan as the final execution plan. The execution plan is then passed to the query executor.6. Query Executor execution QueryThe query executor passes the execution plan through the OLE DB interface to the data access method of the storage engine.7. Data access methods generate execution codeThe data access method executes the code that plans to generate SQL Server actionable dat

Optimizing SQL queries: How to write high-performance SQL statements1, first to understand what is called the implementation plan?An execution plan is a query scheme that the database makes based on the statistics of SQL statements and related tables, which are generated automatically by the query optimizer, such as an

About recursive queries that use a CTE (common table expression)----SQL Server 2005 and above A common table expression (CTE) has an important advantage of being able to reference itself to create a recursive CTE. A recursive CTE is a common table expression that repeats an initial CTE to return a subset of data until the full result set is obtained. When a query references a recursive CTE, it is called a