你能帮我纠正这个代码块吗?
`CREATE OR REPLACE FUNCTION TABLE_EXISTS(name VARCHAR(50))
RETURNS BOOLEAN
AS
BEGIN
DECLARE counttable INTEGER;
SELECT COUNT(1) INTO counttable FROM USER_TABLES WHERE TABLE_NAME=name;
if counttable=0 then
return false
else
return true
end if;
END;
/
IF (TABLE_EXISTS("LEADS_DELETED")) then
DROP TABLE LEADS_DELETED;
end if;
/
CREATE GLOBAL TEMPORARY TABLE LEADS_DELETED
(
ID NUMBER(19),
PRIMARY KEY (ID)
) ON COMMIT DELETE ROWS`