Gbase8s database for read only clause

FOR READ ONLY Clause

Please use FOR READ ONLY Keyword to specify as SELECT Statement Declares Select A cursor is a read-only cursor . only

A read cursor is a cursor that cannot modify data . This section provides information about FOR READ ONLY Clause ：

When do you have to use FOR READ ONLY Clause

For the use of FOR READ ONLY Clause SELECT Syntactic restrictions on sentences

Use as read-only FOR READ ONLY Clause

Usually , You don't have to SELECT The statement includes FOR READ ONLY Clause . According to the definition ,SELECT It is a read-only operation

do , therefore FOR READ ONLY Clauses are usually unnecessary . However , In some circumstances , You must be in SELECT

The statement includes FOR READ ONLY keyword .

In conformity with ANSI In the database of , By default ,Select The cursor is update The cursor .update Cursors can be fixed

Change the cursor of data . these update Cursors are incompatible with the read-only mode of the database . for example , in the light of customer_ansi

This of the table SELECT Statement failure ：

EXEC SQL declare ansi_curs cursor for

select * from customer_ansi;

The solution is in your Select The cursor includes FOR READ ONLY Clause . The read-only cursor specified in this clause is related to the database

Is compatible with read-only mode . for example , The following is for customer_ansi Tabular SELECT FOR READ ONLY Sentence into

work ：

EXEC SQL declare ansi_read cursor for

select * from customer_ansi for read only;

DB-Access With Select The cursor executes all SELECT sentence , therefore , You must be read-only in all accesses that comply with ANSI

Data in the database specified in the query FOR READ ONLY.FOR READ ONLY Clause results in DB-Access take

SELECT The cursor of the statement is declared as a read-only cursor .

To get more information about 0 Level backup information , see also GBase 8s Backup and recovery guide . To get information about Select The cursor 、

Read only cursors and update Cursor information , see also DECLARE sentence .

And FOR READ ONLY Clause incompatible Syntax

If you try at the same SELECT The statement includes FOR READ ONLY Clause and FOR UPDATE Clause , Then

SELECT Statement failure . To get information about not including FOR READ ONLY Clause SELECT Statement Declares a read-only cursor

Information about , see also DECLARE sentence .