1. The name field is used to store the customer's name, and the query result needs to be sorted by surname Pinyin, there is now a problem,Names include both Chinese and English names, such as Zhang San, John Doe, Jaewon Park, Lao WangSo query out the results of the English name of the person forever ranked firstSort I'm using the following sentenceCONVERT ( name USING gbk) COLLATE gbk_chinese_ci
How can the
http://zhangzhaoaaa.iteye.com/blog/1689412 reference: "MySQL Technology insider SQL Programming"SELECT DISTINCT From lefttableOn WhereGroup Bywith{cube| ROLLUP}HavingOrder byLimitProcessing order
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To randomly extract a record from the TableName table, the general wording is: SELECT * from TableName ORDER by RAND () LIMIT 1.
But then I looked up the official MySQL manual, and the hint for rand () probably meant that the rand () function could not be used in an ORDER BY clause because it would cause data columns to be scanned multiple times. However, in the
Recently, a large-screen display project, similar to the airport, the train station, the kind of display shift information, but the content of the show is more complex, some of the data are as follows:Front-end mainly with Vue framework, require back-end data in the front-end display, first: Into the factory, the factory indicator is not fixed (may be 6, may also be 7, 8); second: No "value" values are used in place of a slash ; third: In and out of the factory index name must conform to the nam
Tags: http ar using SP on div problem BS ADWhen using Sphinx in a project, many people encounter the problem of how to sort the specified ID in MySQL after retrieving the correlation ID using Mysql+sphinx. Here is my workaround in the project:
1
SELECT * FROM documents WHERE id IN (5,3,6,1) ORDER BY FIELD(id,5,3,6,1);
Or:
The first segment is non-paging quot; selectT. ID, TName. name, (selectCount (UsingT. TID) fromUsingTwhereUsingT. TIDT. ID) asLinkCountfromTinnerjoinTNameonT. TNameIDTName. IDandTName. namelike @ tnameorderbyNameasc; (selectT. IDfromTinnerjoinTNameonT... mysql database
The first segment is non-paging.
Select T. ID, TName. name, (select Count (UsingT. TID) from UsingT where UsingT. TID = T. ID) as LinkCountfrom T inner join TName on T. TNameID =
Preface:Always want to know how a SQL statement is executed, the order in which it executes, and then review the summary of the information, there is the following blog post. This article explores the knowledge from the MySQL overall architecture---> Query execution process---> statement execution sequence.First, MySQL
Tags: alt from cond test data strong allow MySQL first left joinRead Catalogue
Definition order of a SELECT statement keyword
Order of execution of the two SELECT statement keywords
Three preparation tables and data
Four prepare SQL logical query Test statement
Five Execution sequence analysis
solve paging problems. For small data, using the LIMIT clause has no problem, and when the amount of data is very large, the use LIMIT n, m is very inefficient. Because the mechanism of limit is to scan from scratch every time, if need to start from the No. 600000 line, read 3 data, you need to scan to locate 600,000 rows before reading, and the scanning process is a very inefficient process. Therefore, for large data processing, it is very necessary to establish a certain caching mechanism in
When you index a table, some of the queries will use the order by, the group by, and so on, and in a lower version (with a prior version of ICP), you may experience a situation where the query uses the index, so the order by cannot use the index, and of course we can create the Federated index, So under what circumstances is it valid to create a federated index?
Label: MySQL This function is very useful!! To sort the results of a query in the specified order ---------------------------------------------------------------------- The table structure is as follows:Mysqlgt; SELECT * from Test;+----+-------+| ID | name |+----+-------+| 1 | Test1 || 2 | Test2 || 3 | Test3 || 4 | test4 || 5 | Test5 |+----+-------+ Execute the
This article gives you the content is about MySQL sentence execution sequence and query processing stage analysis, there is a certain reference value, the need for friends can refer to, I hope to help you.
The MySQL statement is divided into 11 steps, as noted, the first execution is always the from operation, and finally the limit operation is performed. Each
MySQL database-basic query, simple query, conditional query, sorting of query results, mysql query results
I. SELECT statements SELECT COL1, COL2,... COLn FROM TABLE1, TABLE2,... TABLEn
IN Oracle databases, order by sorting and query are output IN the ORDER of IN conditions. oracleorder
Order by non-stable sortingQ: Is oracle a stable Sorting Algorithm for order by sorting? After a type is found to be used for sorting, paging
Array( [id] => 1 [user_id] => 1 [year] => 2013-2014 [term] => 1)Array( [id] => 2 [user_id] => 1 [year] => 2013-2014 [term] => 2)Array( [id] => 3 [user_id] => 1 [year] => 2012-2013 [term] => 1)
If the above first in the case of the reverse of year, and then according to term 2 of the first query for 1 after query best with thinkphpIt should be found out.
Array( [id] =>
, special symbol processingThinking answer 1:select ' abc ' from dual;Thinking answer 2:select ' | | ' ABC ' | | ' from dual; 5, WHERE clause: Conditional query, expression satisfies what conditions display data. Combined from use 5.1 Employees with a pay check of more than 1000SELECT * FROM EMP where sal>=1000; --Show all fields of employees with current salary at 1000 and aboveSelect Ename,sal from emp where sal>=1000; --inquire about the names and
In SQL Server, if a table has a clustered index, in most cases, if a select * from tablename query is made, the default return order is returned in the order in which the columns are clustered.However, when a table has a clustered index, it does not necessarily mean that all cases are arranged in the order of the clust
Option (Force Order)Today, share with you. Enforce join order in SQL Option (Force order)SQL itself SQL Engine optimization has done very well, but also has the default multi-table connection engine effect does not reach the value we expect,So we need to enforce our multi-table join order.egCREATE TABLE #Student (RowId int identity (), Name varchar (), age int) G
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