remove table from database

Constraints* The constraint is added to the column, to constrain the column!1. PRIMARY KEY constraint (unique identifier)Non-empty * * *Unique * * *Quoted * * * ** When a column of a table is designated as the primary key, the column cannot be empty

In the first case, append the data from the a database. dbo.a table to the B database. DBO.B table (condition: B table is already created in the B database )Inert into B database. dbo.b tableSELECT * from a database. dbo.a table [WHERE

Http://www.cnblogs.com/RunForLove/p/5693986.htmlThe three paradigms of database design: In order to build a database with small redundancy and reasonable structure, we must follow certain rules when designing database. In a relational database, this

1. Relationship between the original document and the entityCan be a pair of one or one-to-many, many-to-many relationships. In general, they are one-to-one relationships: a single original document corresponds to and corresponds to only an entity.

Information A 1, stop the database server, the database MDF files and LDF files copy backup a copy 2, start the database server, delete the suspect database 3, only with the backup of the database MDF file attached to the database,

database table creation, management, and data manipulation (experiment one), database creationToday we will study the creation, management and data manipulation of tables in the form of experiments."Experimental Purpose": understand the use of SQL

1. Data Tables with tree relationships Many programmers have encountered tree-based data during database design. For example, a common category table, that is, a large category, contains several sub-classes, some sub-classes have sub-classes. When

I. Database Design Process Database technology is the most effective means of information resource management. Database Design refers to constructing the optimal database mode for a given application environment, establishing a database and its

OralceImp help=y; View commands used;Local export of the remote database DMP file locally;1: Set an instance name in Tnsnames.oraOrcl=(DESCRIPTION =(ADDRESS = (PROTOCOL = TCP) (HOST = 192.168.20.110) (PORT = 1521))(connect_data) = (SERVER =

/***********************************************Duplicate records in two meanings:1. is a completely duplicate record, that is, all fields are duplicates of the record,2. is a duplicate record of some key fields, such as username field