Mysql varchar sorting CAST, CONVERT function type conversion, varcharconvert
When creating a table on your own, you should create a field type as varchar (2). In fact, it should be set as integer (2). But today, we found a Sorting Problem in the background and a varchar Sorting Problem, so how can this problem be solved?
Example Table Structure: Let's take a look, my table structure show create table cardserver \ G ***************************** 1. ro
Brief introduction
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Label:An expression that explicitly converts an expression of one data type to another data type. CAST and CONVERT provide similar functionality. Cast SELECT CAST('12.5' as int)--failed to convert varchar value ' 12.5 ' to data type int.
SELECT CAST('12.5' as decimal(5,3))--12.500
SELECT
Tags: http color ar div code SP on time lineMySQL's cast () and CONVERT () functions can be used to get a value of one type and produce a value of another type. The specific syntax for both is as follows:
1
CAST(valueastype);
2
CONVERT(value, type);
is cast (xxx as type), CONVERT (XXX, type).There i
Tags: style http color ar sp div on code timeMySQL's cast () and CONVERT () functions can be used to get a value of one type and produce a value of another type. The specific syntax for both is as follows:View Source print?
1
CAST(value astype);
2
CONVERT(value, type);
is cast (xxx as type), CONVERT
Cast as conversion function in HQLCast (A as B); A is the data to be converted, B is the target type (not the database type name, is the hibernate type name: such as the target type is varchar, must write a string)Eg:select * FROM table where cast (field name to convert as String) 1. SELECT cast (' 2016-12-04′as date) converts string to date type2. SELECT
Explicitly converts a data type expression to another data type. CAST and CONVERT provide similar functions.Syntax
Use CAST:
CAST (expression AS data_type)
Use CONVERT:
CONVERT (data_type [(length)], expression [, style])Parameters
Expression
Is any valid Microsoft SQL Server expression.
Data_type
The data types provided by the target system, including bigint and
Take a note: from the Forum: http://bbs.csdn.net/topics/210039564Summarize all the cast functions in C + + (Const_cast,reinterpret_cast,static_cast,dynamic_cast)C-style (C-style) Forced transformation is as follows:(t) expression/cast expression to BES of type TThe function style (function-style) Force transformation uses this syntax:T (expression)//cast expressi
Treatment of domestic wastewater by CAST v0.9.11 1CD circulating activated sludge processCirculating activated sludge method (a kind of domestic sewage treatment process, it is based on the SBR process, the addition of the selector and sludge return facilities, and the timing of some adjustments, thus greatlyThe reliability and efficiency of SBR process are high. )Compared with the conventional SBR method, the main characteristic of this process is th
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COL3 DATETIME ,
COL4 VARCHAR ()GO INSERT into Teststatistics VALUES (RAND () *10,cast (GETDATE ()-rand () * 1000000 Problem Recurrence First look at a very interesting question, on the same table, first build an index: CREATE index idx_col2_col3 on Teststatistics(COL2,COL3) executes a query, estimated to be 4127.86 rows Then drop the index above and continue creating an index: Create index idx_col3_col2 on
N.categoryid C.categoryid,c.[name]First query statement: Select C.categoryid,c.[name] from Category C left join News N in C.categoryid=n.categoryid where N.categoryid is NullSecond query statement: Select Categoryid,[name] from category where NOT exists(SELECT * FROM News where Category.categoryid=news.categoryid)* The first performance is undoubtedly the best when the CategoryID is not repeated in the news table, whereas the second performance is good.11.SQL Statement conversion Format functio
following method to sort server_id + 0 and then solve the problem.
The Code is as follows:
Select server_id from cardserver where game_id = 1 order by server_id + 0 desc limit 10;+ ----------- +| Server_id |+ ----------- +| 10 || 8 || 7 || 6 || 5 || 4 || 3 || 2 || 1 |+ ----------- +
Use the MySQL function CAST/CONVERT:Mysql provides two types of conversion functions: CAST a
| | 8 | | 7 | | 6 | | 5 | | 4 | | 3 | | 2 | | 1 | +-----------+
Using the MySQL function Cast/convert:MySQL provides us with two types of conversion functions: cast and convert, ready-made things how can we let go?The CAST () and CONVERT () functions can be used to get a value of one type and to produce a value of another type.This type can be
Reference: http://database.51cto.com/art/201005/201651.htmHttp://www.lai18.com/content/1693593.htmlDirectly on the example, the following is the processing of the field cost divided by 1000, leaving two decimal placesCast (SUM (a.costs)/1000 as Decimal (32,2))The cast () function is a conversion function, which is an expression that includes the source value and the target data type separated by the AS keyword.1) Convert the string ' 123 ' to int inte
Label:In SQL Server, both the cast and CONVERT functions are available for type conversions, and their functions are the same. It's just a different syntax. Cast is generally easier to use, and the advantage of convert is that dates and values can be formatted. Select CAST('123' as int)--123
Select CONVERT(int,'123')--123
Select
Overview C # castWww.firnow.com time: 2010-07-02 Author: Network Editor: mr. Abu CLICK: 50 [comment]--Here we use C # cast, and our code is simplified. Cast can even be used on the base class control of all controls. Its CONTROLS attribute is also non-generic!
The Form Control contains a list control (ASP. NET) and a listview control (winform ).
Take listview as an example. The listview control can contain
If SQL ServerProgramA member wants to replace the expression with another one. He can choose from the two built-in functions of SQL Server 7 and 2000. In stored procedures or other situations, we often need to convert data from datetime type to varchar type; convert and cast can be used in this case.Because SQL Server provides two functions, it is easy to confuse which function should be selected or under which situation this function should be used.
Tags: char using sign span SEL statute mysq weight IMAThe CAST function syntax rule is: cast (the type of the field name as conversion), where the type can be: char[(N)] character typeDate typeDateTime Date and Time typeDECIMAL Float TypeSigned intTime Type Example 1: table table1
Date:-one-to- One: -
Selectcastas as from table1;Results: date:20151103153126 select
In SQL Server, both the cast and CONVERT functions are available for type conversions, and their functions are the same.It's just a different syntax.Cast is generally easier to use, and the advantage of convert is that dates and values can be formatted.Select CAST (' 123 ' as int)--123Select CONVERT (int, ' 123 ')--123Select CAST (123.4 as int)--123Select CONVERT
is something. Because I want to explain in this post is the varchar sort problem. So no longer explain how I changed the field type, people are interested to search my previous log. (cheat Click) phenomenon Description: Below, I server_id order from the database inside, we look at the results after the sorting: select server_id from cardserver where game_id = 1 ORDER by server_id D ESC Limit 10;+-----------+| server_id |+-----------+| 8 | | 7 | | 6 | | 5 | | 4 | | 3 | | 2 | | 10 | | 1 |
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