varchar max

Recently, I have participated in several interviews and made many interview questions for the reason I am looking for a job. The most important thing I remember is to judge whether the string is a number, at first, I wrote try... the catch statement

The guidelines to be followed when designing indexes include: Database Rules, query rules, and column rules. Detailed descriptions of each criterion are listed below. Among them, 1-3 belongs to the database criterion; 2-8 belongs to the query

The basic unit of data storage in SQL Server is page. Disk space allocated to data files (. mdf or. ndf) in the database can be logically divided into pages (from 0 to n consecutive numbers ). Disk I/O operations are performed on pages. That is, SQL

/*Function: divides text messages into common text messages.Author: Zhuang Xiang DistrictSelect *From DBO. uf_multimsg ('[benevolence] refers to the affection and goodwill between people. It is the core of Confucianism and traditional morality, and

The main learning T-SQL data type: numeric data type, numeric data type, temporary data type, hybrid data type, with vardecimal decimal storage type. 1. Numeric data type The numeric data type is used to represent the data. See the following table

I found blogengine on www.asp.net and thought it was quite suitable for me to study. So I downloaded it and found that he used SQL Server 2005, but I only had SQL Server 2000, however, the SQL installation script provided by him may encounter errors

-- Note:SQL Server does not continuously test databases that have reached the configured threshold for automatic contraction.Instead, it looks for available databases and finds the first database configured to automatically contract.It will check

Before I start, I want to talk about several concepts. Overwrite Query] When an index contains all the columns referenced by a query, it is usually called "Overwrite query ". [Index coverage] If the returned data column is included in the

The char type in the database is used to store fixed-length strings. The efficiency is slightly higher than that of varchar. However, it consumes more space than varchar. For example, if you store the string "ABC", for char (20), it means that the

Method 1: Use the SQL Server proxy (Alert + Job)The procedure is as follows:1. First, use the following command to enable the trace flag.SQL codeDbcc traceon (3605, 1204, 1222,-1)Note:3605 output the result of DBCC to the error log.1204 return the

In a team project, there is no agreement on Collation, programming in the ms SQL Server will encounter such a problem:Cannot resolve the collation conflict between "Latin1_General_CI_AS" and "SQL _Latin1_General_CP1_CI_AS" in the equal to operation.

A small project has been developed recently. If you encounter such problems, record them as a summary. This project is divided into two parts: News data collection, audit of collected information, and XML file generated at last. After the collected

In SQL Server 2005, you can extend the non-clustered index function by adding non-key columns to the leaf level of the non-clustered index. By including non-key columns, you can create non-clustered indexes that overwrite more queries. This is

Someone asked me how to capture and record the deadlock information on the Forum. Here, I will share some of my experiences with you, and I would like to ask you to correct them. We know that you can useSQLThe profiler tool provided by the server is

As I needed to train my colleagues on database indexing knowledge, I collected and sorted out this series of blogs. This is a summary of index knowledge. After summing up, I found that many vague concepts were much clearer in the past. Whether it is

Basic SQL server indexing knowledge (1)-basic format of Record DataHere we have collected a series of database indexing knowledge, which is a summary and review of the indexing knowledge. By summing up, you will find that many vague concepts are

Declare @ tabletype varchar (max) =''Declare @ tablename varchar (max)Set @ tablename = 'student'Select @ tabletype = @ tabletype+ Case when types. Name in ('varchar ', 'nvarchar', 'Char ', 'nchar', 'varbinary ')Then' ['+ columns. Name +'] '+ ''+

Same combination and column formation   My classmates asked me the question of combining database tables into columns. My first thought was to create a two-dimensional array. The two hash tables correspond to rows and columns respectively, and read

Turn: http://blog.csdn.net/dba_huangzj/article/details/8300784 Many people know the isnull function, but few know the coalesce function. People will accidentally use the coalesce function and find it more powerful than isnull. In fact, this function

Someone asked me how to capture and record the deadlock information on the Forum. Here, I will share some of my experiences with you, and I would like to ask you to correct them. We know that we can use the profiler tool provided by SQL Server to