mssql alter column

--Requirements change, need to add a foreigner name to the F_username field of the T_login table, the previous set of varchar (10) is not enough, the negotiation decision to change to varchar (30), when executing, the message index ' Uq_f_username '

Reading directory (content) 1 Concurrency control theory 1.1 Pessimistic concurrency control 1.2 Optimistic concurrency control 2 Isolation Level 2.1 Isolation Level Description 2.2 Read commmitted

If reproduced, please indicate the source of the blog: www.cnblogs.com/xinysu/, copyright belongs to the blog Garden su Home radish all. Hope you support! MySQL implements concurrency control through MVCC and locks, and in 4 isolation

At work we generally encounter the need to turn Heng lie into a vertical column, the following is a case of Heng lie:1. Build a tableCREATE TABLE [dbo].[Acrosschangeendlong]( [Id] [INT] IDENTITY(1,1) not NULL, [Name] [NVARCHAR]( -) not NULL,

As a database developer, you are responsible for creating and managing databases and tables. When creating a table, maintaining the integrity of the data is important to you. To ensure that the data in the table is accurate, consistent, and reliable,

Currently, table partitions exist in almost all databases, but some details about MSSQL table partitions are different. I also have some knowledge about them. Therefore, this article does not explain the principles in detail, this section describes

Environmental requirements: 2005+In everyday needs, there is often a need to deal with rows and columns. Assuming that it is not a dynamic line, we can take a case and then list the processing.When SQL 2005 used to handle dynamic rows or columns, it

Environmental requirements: 2005+In daily needs, there are often rows of things to do, if not dynamic rows, then we can take the case when the list of processing.When dealing with dynamic rows or columns before SQL 2005, it is usually done by

Whether it is a product, or information, quality is very important. The quality of information refers to the accuracy, completeness and consistency of information. In many database application systems, the quality of data is often the most important

MSSQL Update from syntax Copy Code code as follows: Update a set a.columnname=b.columnname from A,b where b.id=1 1. system table sysobjects Each object created in the database (such as constraints, defaults, logs, rules, and