Books
in black and white
Main menu
Share a book About us Home
Books
Biology Business Chemistry Computers Culture Economics Fiction Games Guide History Management Mathematical Medicine Mental Fitnes Physics Psychology Scince Sport Technics
Ads

Teradata RDBMS forUNIX SQL Reference - NCR

NCR Teradata RDBMS forUNIX SQL Reference - NCR, 1997. - 913 p.
Download (direct link): teradataforunix1997.pdf
Previous << 1 .. 153 154 155 156 157 158 < 159 > 160 161 162 163 164 165 .. 241 >> Next

ALL The ALL keyword, used in place of a hostid, applies to any source through which a logon is attempted, including the Teradata RDBMS console.
AS DEFAULT Specifies that the current default for the specified hostid(s) is to be changed, without residual conditions, as defined in this GRANT LOGON statement. A statement with AS DEFAULT has no effect on the access granted to or revoked from particular usernames (see Usage Notes). A statement that sets the default for a specific hostid takes precedence over a statement that sets the default for ALL client systems.

8-166

Teradata RDBMS for UNIX SQL Reference
Teradata SQL Syntax Guide

GRANT LOGON

Privileges

GRANT LOGON for One or More Usernames

If No Logon Control Record for a Username

Syntax Element... Description
TO FROM dbname [...,dbname] Overrides the current default for the specified username(s) on the specified hostid(s). • The name DBC cannot be specified as a username in a GRANT LOGON statement (see Usage Notes). A statement that includes this name will return an error message. • The product of the number of hostids times the number of usernames cannot exceed 25.
WITH NULL PASSWORD The initial Teradata RDBMS default is that all logon requests must include a password. The WITH NULL PASSWORD option, in conjunction with a TDP security exit procedure (see Usage Notes), permits a logon string that has no password to be accepted from the specified client system community.

A statement that includes the AS DEFAULT option has no effect on the logon access granted to or revoked from specific usernames; a user named in a GRANT LOGON statement can always access the applicable client system even if that client has a default of REVOKE, and a user named in a REVOKE LOGON statement cannot access the applicable client system even if that client has a default of GRANT.

When a GRANT LOGON statement is submitted, the system checks that the requesting user has EXECUTE privilege on the system macro associated with that statement. However, no checks are made on whether the usernames defined in the statement apply to users owned by the requesting user. If the submitted statement cannot be verified because, for example, it specifies an invalid username or an invalid hostid, no action is taken on the statement.

When a GRANT LOGON statement is processed for one or more usernames, a logon control record is created for each username/hostid pair specified. Any existing control record for a particular username/hostid pair is replaced. The logon control record(s) created for a particular username will stay in existence until that user is dropped (see “DROP DATABASE, DROP USER”).

If there is no logon control record for a specific username, access to the Teradata RDBMS under that name is governed by the current default for the hostid through which the logon is entered.

Teradata RDBMS for UNIX SQL Reference

8-167
Teradata SQL Syntax Guide

GRANT LOGON

Logging on as DBC

Logging on Without a Password?

Any attempt to log on to the Teradata RDBMS with username DBC requires a password. If the submitted password is correct, the logon is accepted regardless of the current default for the applicable hostid. This prevents any opportunity to lock out all client systems from the Teradata RDBMS.

Attempts to GRANT LOGON for username DBC will result in errors.

When the Teradata RDBMS is connected to multiple client systems, the initial default is that logon permission is granted to all users from all client system connections, and that all logons must include a password.

For a user to log on without a password, two factors must exist:

• A GRANT LOGON statement that includes the WITH NULL PASSWORD option must be executed for the defined username or must be the default for the hostid.

• A security exit installed in the TDP or CLI must acknowledge that the logon string for this username is valid without a password (UNIX CLI and WINCLI support exits).

8-168

Teradata RDBMS for UNIX SQL Reference
Teradata SQL Syntax Guide

GROUP BY Clause

GROUP BY Clause

The GROUP BY clause of the SELECT statement groups result rows by the values in one or more columns.

See Chapter 7, “Queries: The SELECT Statement,” “GROUP BY Clause”, for a detailed description of GROUP BY.

Teradata RDBMS for UNIX SQL Reference

8-169
Teradata SQL Syntax Guide

HAVING Clause

HAVING Clause

The HAVING clause in the SELECT statement specifies a conditional expression that must be satisfied by the rows to be included in the resulting data. The condition may define one or more aggregates (MAX, MIN, AVG, SUM, COUNT), and may be applied to the rows of:

• A single group defined in the select expr-list, which has only aggregate results

• One or more groups defined in a GROUP BY clause

Refer to Chapter 7, “Queries: The SELECT Statement,” “HAVING Clause”, for a detailed description of the HAVING clause.

8-170

Teradata RDBMS for UNIX SQL Reference
Previous << 1 .. 153 154 155 156 157 158 < 159 > 160 161 162 163 164 165 .. 241 >> Next