Obtain the latest ID by SQL, scope_identity (), @ identity, ident_current

-- Scope_identity () the return value of this method is null, because it returns the last value of the identity in the current session and scope.

-- @ Identity: returns the value of identity in any scope in the current session.

-- Ident_current ('table name') returns the value of the last identity of the specified table, regardless of the session and scope.

@ Identity
Returns the last inserted id value.
 
Syntax
@ Identity
 
Return type
Numeric
 
Note
After an insert, select into, or large-capacity copy statement is completed, @ identity contains the final id value generated by this statement. If this statement does not affect any table with an ID column, @ identity returns NULL. If multiple rows are inserted, multiple ID values are generated. @ identity returns the final id value. If one or more triggers are triggered to execute the insert operation that generates the id value, @ identity is called immediately after the statement is executed, and the last id value generated by the trigger is returned. If the insert or select into statement fails, the large-capacity copy fails, or the transaction is rolled back
The @ identity value is not restored to the previous setting.
 
The functions of @ identity, scope_identity, and ident_current are similar in returning the last value of the @ identity column inserted to the table.
 
@ Identity and scope_identity return the last id value generated in all tables of the current session. However, scope_identity only returns values within the current scope, and @ identity is not limited to specific scopes.
 
Ident_current is not restricted by the scope and session, but by the specified table. Ident_current returns the id value generated for a specific table in any session and in any scope.

-------- A separation line -------------

Differences between the three methods that return the maximum value:
 
Ident_current returns the last generated id value for any session and specific tables in any scope.
 
 
@ Identity returns the last generated id value for any table in all scopes of the current session.
 
 
Scope_identity returns the last generated id value for the current session and any table in the current scope. (Prevent returning the identity value of insert in the trigger)

-------- Another one -------------

@ Identity
Returns the last inserted id value.
 
Syntax
@ Identity
 
Return type
Numeric

-------- Another one -------------

Note
After an insert, select into, or large-capacity copy statement is completed, @ identity contains the final id value generated by this statement. If this statement does not affect any table with an ID column, @ identity returns NULL. If multiple rows are inserted, multiple ID values are generated. @ identity returns the final id value. If one or more triggers are triggered to execute the insert operation that generates the id value, @ identity is called immediately after the statement is executed, and the last id value generated by the trigger is returned. If the insert or select into statement fails, the large-capacity copy fails, or the transaction is rolled back
The @ identity value is not restored to the previous setting.
 
The functions of @ identity, scope_identity, and ident_current are similar in returning the last value of the @ identity column inserted to the table.
 
@ Identity and scope_identity return the last id value generated in all tables of the current session. However, scope_identity only returns values within the current scope, and @ identity is not limited to specific scopes.
 
Ident_current is not restricted by the scope and session, but by the specified table. Ident_current returns the id value generated for a specific table in any session and in any scope. For more information, see ident_current.