参数

stmt

仅以过程化样式：由 mysqli_stmt_init() 返回的 statement 标识。

attr

The attribute that you want to set. It can have one of the following values:

Attribute values

Character	Description
MYSQLI_STMT_ATTR_UPDATE_MAX_LENGTH	Setting to TRUE causes mysqli_stmt_store_result() to update the metadata MYSQL_FIELD->max_length value.
MYSQLI_STMT_ATTR_CURSOR_TYPE	Type of cursor to open for statement when mysqli_stmt_execute() is invoked. mode can be MYSQLI_CURSOR_TYPE_NO_CURSOR (the default) or MYSQLI_CURSOR_TYPE_READ_ONLY.
MYSQLI_STMT_ATTR_PREFETCH_ROWS	Number of rows to fetch from server at a time when using a cursor. mode can be in the range from 1 to the maximum value of unsigned long. The default is 1.

If you use the MYSQLI_STMT_ATTR_CURSOR_TYPE option with MYSQLI_CURSOR_TYPE_READ_ONLY, a cursor is opened for the statement when you invoke mysqli_stmt_execute(). If there is already an open cursor from a previous mysqli_stmt_execute() call, it closes the cursor before opening a new one. mysqli_stmt_reset() also closes any open cursor before preparing the statement for re-execution. mysqli_stmt_free_result() closes any open cursor.

If you open a cursor for a prepared statement, mysqli_stmt_store_result() is unnecessary.

mode

The value to assign to the attribute.