Sybase 12.4.2 用户手册

Control statements

 

FROM customer

WHERE nationality(id) = ’CDN’

Declarations of cursors and exceptions are discussed in later sections.

An atomic statement is a statement that is executed completely or not at all. 
For example, a 

LOAD 

statement that inserts thousands of rows might encounter 

an error after many rows. If the statement does not complete, and the default 

ON FILE ERROR ROLLBACK

 option is in effect, all changes are undone. This 

LOAD 

statement is atomic.

All noncompound SQL statements are atomic. A compound statement can be 
made atomic by adding the keyword 

ATOMIC 

after the 

BEGIN 

keyword.

BEGIN ATOMIC

INSERT INTO 

sales_order (id, order_date, sales_rep)

VALUES (41880, 1998-08-24, 2054) ;

INSERT INTO 

sales_order_items (line_id, prod_id, quantity, 

ship_date) 

VALUES (01, 43629, 15, ’bad_data’) ;

END;

In this example, the two 

INSERT 

statements are part of an atomic compound 

statement. They must either succeed or fail as one. The first 

INSERT 

statement 

would succeed. The second one causes a data conversion error since the value 
being assigned to the 

ship_date

 column cannot be converted to a date.

The atomic compound statement fails and the effect of both 

INSERT 

statements 

is undone. Even if the currently executing transaction is eventually committed, 
neither statement in the atomic compound statement takes effect.

COMMIT 

and 

ROLLBACK 

and some 

ROLLBACK TO SAVEPOINT 

statements are 

not permitted within an atomic compound statement. See “Transactions and 
savepoints in procedures” on page 265.

There is a case where some, but not all, of the statements within an atomic 
compound statement are executed. This is when an error occurs, and is handled 
by an exception handler within the compound statement. 

 For more information, see “Using exception handlers in procedures” on page 
261.