steps to optimize sql query

=15 (not connected, accepting connect from any host)Test Mysql-cluster1. Create a table on the management machinemysql> CREATE database D1;mysql> use D1;mysql> CREATE TABLE ' t_e ' (' Emp_no ' int (one) is not NULL,' Birth_date ' date not NULL,' first_name ' varchar (not NULL),' last_name ' varchar (+) not NULL,' Gender ' enum (' M ', ' F ') is not NULL,' Hire_date ' date not NULL,PRIMARY KEY (' Emp_no ')) Engine=ndbcluster DEFAULT Charset=utf82.mysql> INSERT INTO t_e select * from Employees.emp

the two steps to the right is also changed. This is enough to show that when optimizing a view, it is best to apply different filtering conditions to the actual requirements, and then decide how to optimize. Here's a three-query-composition scenario to see the implementation plan for this view. SELECT * FROM dbo. Ordersview where OrderId = 1;SELECT * FROM dbo

longitude and latitude two columns in the data table to optimize the speed at which the where statement executes.The final SQL statement is as follows 1 $sql=‘select * from users_location where 2 latitude >‘.$lat.‘-1and 3 latitude ‘.$lat.‘+1and 4

although the view is defined by a query statement, it may not make much sense to parse the query definition, because the view is not used directly, but before it is used, it is preceded by a where statement, or in other statements for use by the FROM clause. Here's an example of a view Ordersview in my demo database, defined in front of the code. Let's take a look at what kind of execution plan comes in if

example:In this table, CITY_ID is the primary key, the City field is a varchar type, the length is 50, the default is null, and the explain select city from Sakila.city is executed as follows:Can be found here to go to overwrite the index, by the way, the overwrite index is the SQL query content through the SQL index to be able to find out, this is the overwrite

This article will introduce you to the basic operation, configuration, and steps for connecting SQL SERVER and DB2 in WINDOWS, and the test environment for your reference. The interconnection of different database platforms is generally called the heterogeneous service of databases. Currently, all major databases can achieve such Heterogeneous Interconnection, but the specific implementation technologies of

Tags: style blog http color io os ar using JavaThe steps for JDBC to connect to a SQL Server database are as follows: 1. Load the JDBC driver (only once): Before connecting to the database, first load the driver of the database you want to connect to the JVM (Java Virtual machine), which is forname by the static method of the Java.lang.Class class (String className Achieve After a successful load, an i

the full table scan to block several times or even thousands of times!(33) Avoid using resource-intensive operations:SQL statements with Distinct,union,minus,intersect,order by will start the SQL engine to perform the resource-intensive sorting (sort) function. Distinct requires a sort operation, while the others need to perform at least two sorting. Typically, SQL statements with UNION, minus, and interse

Tags: create delete Table database data management Permissions code data case-sensitive large nameSQL Structured Query language for all SQL databases　　SQL requires a semicolon (;) at the end of each instruction and a standard method for executing more than one SQL statement in the same request to the server.The ultimat

ordersview, the definition code is preceded by. Let's take a look at what the execution plan would be if we were to use this view directly:As you can see from this view, SQL Server does a full table scan of table orders and should be inefficient. Take a look at the following query:As you can see from this execution plan, it's not the same as the one above. The lookup of the Orders table in the previous query