tailieunhanh - Oracle SQL Plus The Definitive Guide- P6

Oracle SQL Plus The Definitive Guide- P6:Every day, computer professionals the world over wake up, travel to the office, sit down in front of a computer, and begin another day working with that database called Oracle. Programmers write queries and stored procedures. Database administrators monitor performance, make database changes, and perform other maintenance tasks. Operations people may need to back up or recover a database. | previous page page_27 next page Page 27 There are some optional arguments to the EXIT command which may be used to return success or failure values to the operating system. These are useful when running scripts in batch mode and are described fully in Chapter 7 Advanced Scripting. Password The PASSWORD command allows you to change your database password. The PASSWORD command was introduced beginning with SQL Plus version 8. In prior versions you need to use the ALTER USER command to change a password. To change other people s passwords you need the ALTER USER system privilege. The syntax for the PASSWORD command is PASSWORD username where PASSW ORD May be abbreviated to PASSW. username Is the user whose password you want to change. Usually only database administrators DBAs can change passwords for other users. You do not need to supply a username if you are changing your own password. Here is an example showing how the PASSWORD command is used SQL PASSWORD Changing password for JONATHAN Old password New password Retype new password Password changed If you are running a version of SQL Plus prior to version 8 the PASSWORD command will not be available. Instead use the ALTER USER command to change your password. Here s how SQL ALTER USER jonathan IDENTIFIED BY wonker As you can see the PASSWORD command has the advantage of not showing the new password on the screen. previous page page_27 next page previous page page_28 next page Page 28 Help The HELP command is used to get help on SQL statements SQL Plus commands and PL SQL commands. SQL Plus released with Oracle8i provides help only on SQL Plus commands. This is because there wasn t time for Oracle to update the help text to cover all the new functionality in SQL and PL SQL in time for the 8i release. Subsequent versions of SQL Plus should reenable SQL and PL SQL help. The syntax for HELP is HELP topic where Help May not be abbreviated. topic Is the help topic you want to read about. Most SQL commands SQL Plus .

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