Shulou(Shulou.com)06/01 Report--

1. Local variables:

Local variables must be prefixed with the tag @, such as @ Age int

Local variables: declare and then assign

DECLARE @ variable name data type

DECLARE @ bookName varchar (20) SET @ bookName =''

two。 Global variable (system variable):

Global variables must be prefixed with the tag @ @, such as @ @ version

Global variables are defined and maintained by the system. We can only read them, not modify their values.

Variable meaning

@ @ ERROR the error number of the last T-SQL error

The last inserted identity value of @ @ IDENTITY

@ @ the name of the language currently used by LANGUAGE

The maximum number of simultaneous connections that can be created by @ @ MAX_CONNECTIONS

@ @ ROWCOUNT the number of rows affected by the previous SQL statement

@ @ name of the SERVERNAME local server

@ @ TRANSCOUNT the number of transactions currently open to the connection

Version information of @ @ VERSIONSQL Server

Set is used for ordinary assignment SET @ bookName = 'unsolved riddle'

SELECT is used to query data from a table and assign values such as: SELECT @ bookName=Name FROM Book WHERE ID=2

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