session_unique_id

NAME

session_unique_id(): Return a unique unsigned integer for this session

TYPE

Function

DESCRIPTION

This function returns unique values per session. That is, any two calls to this function from within the same session, result with different, unique values.

The function utilizes the fact that a session is managed serially (it it generally unsafe and undesired to issue concurrent queries on same connection). Therefore, it is known that any two calls on this function are essentially serialized within the session

Current implementation of this function is to return incrementing unsigned integer values. However, the user should not rely on this behavior, and should not assume consecutive results on consecutive calls.

SYNOPSIS

session_unique_id()
  RETURNS INT UNSIGNED

Output:

  • A unique value within current session.

EXAMPLES

Get unique values: 

mysql> SELECT session_unique_id(), session_unique_id();
+---------------------+---------------------+
| session_unique_id() | session_unique_id() |
+---------------------+---------------------+
|                   1 |                   2 |
+---------------------+---------------------+
1 row in set (0.02 sec)

mysql> SELECT session_unique_id();
+---------------------+
| session_unique_id() |
+---------------------+
|                   3 |
+---------------------+


ENVIRONMENT

MySQL 5.1 or newer


AUTHOR

Shlomi Noach
 
common_schema documentation