一个session cursor只能对应一个shared cursor,而一个shared cursor却可能同时对应多个session cursor。 当某个session cursor和其对应的shared cursor建立关联后,如果把cursor_space_for_time调成true,当一个session cursor处理完一条sql后,它就不会被destroy,Oracle会把其cache起来(我们称之为soft closed session curso...
当某个session cursor和其对应的shared cursor建立关联后,如果把cursor_space_for_time调成true,当一个session cursor处理完一条sql后,它就不会被destroy,Oracle会把其cache起来(我们称之为soft closed session cursor),这么做的目的是很明显的,因为这个soft closed掉的sessioncursor已经和包含其执行计划和parse tree的...
PL/SQL also lets you declare explicit cursors. Anexplicit cursorhas a name and is associated with a query (SQLSELECTstatement)—usually one that returns multiple rows. After declaring an explicit cursor, you must open it (with theOPENstatement), fetch rows one at a time from the result set...
2. 显式游标PL/SQL also lets you declare explicit cursors. An explicit cursor has a name and is associated with a query (SQLSELECT statement)—usually one that returns multiple rows. After declaring an explicit cursor, you must open it (with theOPEN statement),...
count() Returns a count of the number of data items for the key to which the cursor refers. long countEstimate() Returns a rough estimate of the count of the number of data items for the key to which the cursor refers. OperationStatus delete() Deletes the record to which the curs...
INVALID_CURSOR 在不合法的游标上进行操作 INVALID_NUMBER 内嵌的 SQL 语句不能将字符转换为数字 NO_DATA_FOUND 使用select into 未返回行,或应用索引表未初始化的 TOO_MANY_ROWS 执行select into 时,结果集超过一行 ZERO_DIVIDE 除数为 0 SUBSCRIPT_BEYOND_COUNT 元素下标超过嵌套表或 VARRAY 的最大值 SUBSCRIPT...
代码运行次数:0 运行 AI代码解释 dropfunctionf1;create or replacefunctionf1(ini int,out j int)returns setof intas$$ beginj:=i+1;returnnext;j:=i+2;returnnext;return;end$$ language plpgsql;select*fromf1(42);j---4344 但在内核实现中,并不是逐条返回的,return next其实只起到了缓存数据的功能...
CURSOR C IS SELECT rowid FROM EMP WHERE empno = :EMP.Empno; BEGIN INSERT INTO EMP( empno, ename, job, mgr, hiredate, sal, comm, deptno ) VALUES ( :EMP.Empno, :EMP.Ename, :EMP.Job, :EMP.Mgr, :EMP.Hiredate, :EMP.Sal,
What is a cursor? A cursor is a pointer to a location in a stream. This location could be a pointer to a specific offset or time in a partition, or to a group's current location. What is an offset? Each message within a partition has an identifier called offset. Consumers can read...
rand, count(*) from t1 where rand in (100, 200, 300) and v1 is not null group by rand order by count(*) / RAND COUNT(*) --- --- 300 2 200 25 100 114 3 rows selected. select * from table(dbms_xplan.display_cursor(format=>'allstats last')); PLAN_TABLE_OUTPUT --...