'select * from [table

'select * from [table_name]'是秘密的游标？('select * from [table_name]' is secretly a cursor?)

几天前，在采访中，我被问到select * from [table_name]中的select * from [table_name]是否是一个游标，因为它一次获取多条记录？

如果是，那么哪种类型？ 显式还是隐式 ，为什么？

请，如果有人能详细说明这将是一个很大的帮助。

A few days back I was asked during an interview if select * from [table_name] is a cursor since it fetches a number of records at a time?

If yes then of which type? Explicit or Implicit and why ?

Please, if anyone can elaborate on this it would be a great help.

最满意答案

显式游标是那些明确打开，提取数据，关闭的游标。

如上所述，光标的使用有两个部分：

游标的定义 游标的用法

游标的定义可以是

CURSOR c IS SELECT col1，col2 FROM table_name

要么

对于我IN（选择col1，col2 FROM table_name）

接下来的区别是：

显式游标需要

打开，取出，退出时，关闭

隐式游标在FOR LOOP语句中执行上述所有步骤。

总而言之，SELECT语句是一个隐式游标。

Best，Mikcutu。

The explicit cursors are those whcih explicitly are opened, fetched data, closed.

As stated, the usage of cursor have 2 parts:

definition of the cursor usage of cursor

Definition of the cursor can be as

CURSOR c IS SELECT col1, col2 FROM table_name

or

FOR i IN (SELECT col1, col2 FROM table_name)

The differences comes next:

The explicit cursor needs

OPEN, FETCH, EXIT WHEN, CLOSE

The implicit cursor performs all above steps in the FOR LOOP statement.

Concluding, a SELECT statement is an implicit cursor.

Best, Mikcutu.