Varchar上的索引是否会产生性能差异?
Does index on a varchar column make the query run slower? I can make that be int. and I don't need to do the LIKE % comparison. varchar列上的索引是否使查询运行得更...
将varchar数据类型转换为日期时间数据类型导致asp.net c#中的超出范围值
I want to insert DateTime variable from ASP.Net C# into an SQL Server database. I get this error for some reason. 我想将ASP.Net C#中的DateTime变量插入到SQL Serv...
mysql列类型char,varchar,text,tinytext,mediumtext,longtext的比较与选择
储存不区分大小写的字符数据TINYTEXT 最大长度是 255 (2^8 – 1) 个字符。TEXT 最大长度是 65535 (2^16 – 1) 个字符。MEDIUMTEXT 最大长度是 16777215 (2^24 – 1) 个字符。LONGTEXT 最大长度是 4294967295 (2^32...
在oracle中varchar和varchar2有什么区别?
1.varchar2把所有字符都占两字节处理(一般情况下),varchar只对汉字和全角等字符占两字节,数字,英文字符等都是一个字节;2.VARCHAR2把空串等同于null处理,而varchar仍按照空串处理;3.VARCHAR2字符要用几个字节存储,要看数据库使用的字符集,大部分情况下建议使用v
SQL Server数据类型nvarchar和varchar是不兼容的错误
I've inherited a C# app which I've converted to vb. I get one error which as far as I can see has nothing to do with the conversion. 我继承了一个c#应用程序,我将它转...
BLOB和VARCHAR用于在MySQL表中存储数组
I've got a design decision to make and am looking for some best practice advice. I have a java program which needs to store a large number (few hundre...
索引将提高varchar(最大)查询性能,以及如何创建索引
Firstly, I should point out I don't have much knowledge on SQL Server indexes. 首先,我应该指出我对SQL Server索引没有太多的知识。 My situation is that I have an SQL Serve...
性能Mysql使用varchar加入或表
If I have a table like this: 如果我有这样的表: CREATE TABLE IF NOT EXISTS `codetransactions` (`id` int(11) NOT NULL AUTO_INCREMENT,`id_customer` int(11) DEFAU...
SQL Server CheckSum是否计算CRC?如果不是,我怎样才能让MS SQL计算任意varchar列的CRC?
Does SQL Server CheckSum calculate a CRC? If not how can I get SQL Server to calculate a CRC on an arbitrary varchar column? SQL Server CheckSum是否计算CR...
如何将VARCHAR转换为NVARCHAR mysql?
Say I have: 说我有: ID Title ------------------------------------------------------| 1 | ماهر زين ...
What size do you use for varchar(MAX) in your parameter declaration?
What size do you use for varchar(MAX) in your parameter declaration?In this case you use -1.See also MSDN docs: msdn.microsoft.com/en-us/library/bb399...
MySql学习之varchar类型
MySQL 数据库的varchar类型在4.1以下的版本中的最大长度限制为255,其数据范围可以是0~255或1~255(根据不同版本数据库来定),在 MySQL5.0以上的版本中,varchar数据类型的长度支持到了65535,也就是说可以存放65532个字节的数据,起始位和结束位占去了3个字节,...
在Gridview DataBound中显示基于varchar列的CheckBox
SQL Server table structure: SQL Server表结构: ChapName varchar(200)Status varchar(1) Requirement: 需求: I want to display checkbox in an AS...
我可以用VARCHAR作为主键吗?
I have a table for storing coupons/discounts, and I want to use the coupon_code column as the primary key, which is a VARCHAR. 我有一个存储优惠券/折扣的表,我想使用coup...
sqlite中varchar数据类型的最大大小限制是多少?
I'm new to sqlite. I want to know the maximum size limit of varchar data type in sqlite? 我是sqlite的新手。我想知道sqlite中varchar数据类型的最大大小限制? can anybody sugges...
Microsoft SQL Server 2005/2008:XML与text / varchar数据类型
Does it make more sense (except of server side validation XML/schema/dtd) to store XML in XML type instead of text/varchar/ntext? I'm not planning to ...
SQL server 字段合并CAST(org_no AS VARCHAR(20))+CAST(page_no AS VARCHAR(20))+CAST(djlb_no AS VARCHAR(20)))
sqlserver字段合并(CAST)----------------------select (CAST(org_no AS VARCHAR(20))+CAST(page_no AS VARCHAR(20))+CAST(djlb_no AS VARCHAR(20))) from ERP_BASIC...
使用文本或VARCHAR哪个数据类型更好?
This question is based on two things performance and size 这个问题是基于两件事的表现和大小。 Which DATATYPE is better to use TEXT or VARCHAR? Based on performance whic...
varchar值的转换溢出了int列
For some value of @nReservationID: 对于@nReservationID的某些值: SELECT @phoneNumber= CASE WHEN ISNULL(rdg2.nPhoneNumber ,0) = 0 THEN ISNULL(rdg2.nMob...
答:SQLServer DBA 三十问之一: char、varchar、nvarchar之间的区别(包括用途和空间占用);xml类型查找某个节点的数据有哪些方法,哪个效率高;使用存储 过程和使用T-SQL查询数据有啥不一样;
http://www.cnblogs.com/fygh/archive/2011/10/18/2216166.html1. char、varchar、nvarchar之间的区别(包括用途和空间占用);xml类型查找某个节点的数据有哪些方法,哪个效率高;使用存储过程和使用T-SQL查询数据有啥不一样;...