PDOStatement::closeCursor()

(PHP 5 >= 5.1.0, PHP 7, PECL pdo >= 0.9.0)

关闭游标，使语句能再次被执行。

说明

PDOStatement::closeCursor()释放到数据库服务的连接，以便发出其他 SQL 语句，但使语句处于一个可以被再次执行的状态。

当上一个执行的 PDOStatement 对象仍有未取行时，此方法对那些不支持再执行一个 PDOStatement 对象的数据库驱动非常有用。如果数据库驱动受此限制，则可能出现失序错误的问题。

PDOStatement::closeCursor()要么是一个可选驱动的特有方法（效率最高）来实现，要么是在没有驱动特定的功能时作为一般的PDO 备用来实现。一般的备用语义上与下面的 PHP 代码相同：

返回值

成功时返回TRUE，或者在失败时返回FALSE。

范例

一个PDOStatement::closeCursor()的例子

在下面例子中，$stmtPDOStatement 对象返回多行，但应用程序只取第一行，让 PDOStatement 对象处于一个有未取行的状态。为确保应用程序对所有数据库驱动都能正常运行，在执行$otherStmtPDOStatement 对象前，$stmt调用一次 PDOStatement::closeCursor()。

参见

• PDOStatement::execute() 执行一条预处理语句

In case this is helpful to anybody else who ends-up here after getting the following error:
SQLState: 24000 [Microsoft][ODBC SQL Server Driver]Invalid cursor state
PDOStatement :: closeCursor() did not fix the issue for me. However, adding SET NOCOUNT ON to the beginning of my stored procedure did.

If you ran a SQL statement (vs a query that returns data) such as UPDATE, try unsetting your PDOStatement object instead of calling PDOStatement::closeCursor().

At least with MySQL this function also resets any bound columns, so the fetches will go through as expected but you will be getting stale data in the loop.
Redo all the binds before continuing!

When running multiple queries one after another especially when stored procedures are involved one must release all result sets and fetch all rows in each result set for a stored procedure before moving onto the next query. This is important because a stored procedure returns an extra (empty) result set as a result of having called the procedure itself. 
In my case calling PDOStatement :: closeCursor() did not work (on php-5.1.3-rc2) and I was presented with the following error message: "SQLSTATE[HY000]: General error: 2013 Lost connection to MySQL server during query" upon trying to PDO :: prepare() my second query. So I used the following drop in replacement within one of my classes which fixed the issue. 

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