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3.5 THE HELP AND TABLE STATEMENTS
ISQL supports an on-line help facility that can be invoked by using the HELP statement. Typ-
ing HELP at the ISQL prompt will display a help file which will list the options accepted by
the HELP statement. The various forms of the HELP statement are listed below:
• HELP - Displays the options that can be specified for HELP.
• HELP COMMANDS - Displays all the statements that ISQL accepts.
• HELP command_name - Displays help file corresponding to the specified statement.
TABLE is an ISQL statement that displays all the tables present in the database including any
system tables. TABLE can be used also to display the description of a single table by explicitly
giving the table name. Both forms of the TABLE statement are shown below:
TABLE;
TABLE table_name;
3.6 TRANSACTION SUPPORT
A transaction is started with the execution of the first SQL statement. A transaction is commit-
ted using the COMMIT WORK statement and rolled back using the ROLLBACK WORK
statement.
If the AUTOCOMMIT option is set to ON, then ISQL treats each SQL statement as a single
transaction. This prevents the user from holding locks on the database for an extended period
of time. This is very critical when the user is querying an on-line database in which a transac-
tion processing application is executing in real time.
A set of SQL statements can be executed as part of a transaction and committed using the
COMMIT WORK statement. This is shown below:
<SQL statement>
<SQL statement>
<SQL statement>
COMMIT WORK ;
Instead, a transaction can also be rolled back using the ROLLBACK WORK statement as
shown:
<SQL statement>
<SQL statement>