This variable applies when binary logging is enabled. It controls whether stored function creators can be trusted not to create stored functions that will cause unsafe events to be written to the binary log. If set to 0 (the default), users are not permitted to create or alter stored functions unless they have the SUPER privilege in addition to the CREATE ROUTINE or ALTER ROUTINE privilege. A setting of 0 also enforces the restriction that a function must be declared with the DETERMINISTIC characteristic, or with the READS SQL DATA or NO SQL characteristic. If the variable is set to 1, MySQL does not enforce these restrictions on stored function creation. This variable also applies to trigger creation. See Section 23.7, “Binary Logging of Stored Programs”.

簡單介紹一下，當二進制日誌啟用後，這個變量就會啟用。它控制是否可以信任存儲函數創建者，不會創建寫入二進制日誌引起不安全事件的存儲函數。如果設置為0（默認值），用戶不得創建或修改存儲函數，除非它們具有除CREATE ROUTINE或ALTER ROUTINE特權之外的SUPER權限。 設置為0還強制使用DETERMINISTIC特性或READS SQL DATA或NO SQL特性聲明函數的限制。 如果變量設置為1，MySQL不會對創建存儲函數實施這些限制。 此變量也適用於觸發器的創建。 請參見第23.7節“Binary Logging of Stored Programs”。

下面我們測試一下，當開啟二進制日誌後，如果變量log_bin_trust_function_creators為OFF，那麽創建或修改存儲函數就會報“ERROR 1418 (HY000): This function has none of DETERMINISTIC, NO SQL, or READS SQL DATA in its declaration and binary logging is enabled (you might

那麽為什麽MySQL有這樣的限制呢？ 因為二進制日誌的一個重要功能是用於主從復制，而存儲函數有可能導致主從的數據不一致。所以當開啟二進制日誌後，參數log_bin_trust_function_creators就會生效，限制存儲函數的創建、修改、調用。那麽此時如何解決這個問題呢？官方文檔介紹如下，具體可以參考23.7 Binary Logging of Stored Programs

If you do not want to require function creators to have the SUPER privilege (for example, if all users with the CREATE ROUTINE privilege on your system are experienced application developers), set the global log_bin_trust_function_creators system variable to 1. You can also set this variable by using the --log-bin-trust-function-creators=1 option when starting the server. If binary logging is not enabled, log_bin_trust_function_creators does not apply. SUPER is not required for function creation unless, as described previously, the DEFINER value in the function definition requires it.

· It will make a slave different from the master.

· Restored data will be different from the original data.

To deal with these problems, MySQL enforces the following requirement: On a master server, creation and alteration of a function is refused unless you declare the function to be deterministic or to not modify data. Two sets of function characteristics apply here:

· The DETERMINISTIC and NOT DETERMINISTIC characteristics indicate whether a function always produces the same result for given inputs. The default is NOT DETERMINISTIC if neither characteristic is given. To declare that a function is deterministic, you must specify DETERMINISTIC explicitly.

· The CONTAINS SQL, NO SQL, READS SQL DATA, and MODIFIES SQL DATA characteristics provide information about whether the function reads or writes data. Either NO SQL or READS SQL DATA indicates that a function does not change data, but you must specify one of these explicitly because the default is CONTAINS SQL if no characteristic is given.

1： 如果數據庫沒有使用主從復制，那麽就可以將參數log_bin_trust_function_creators設置為1。

mysql> set global log_bin_trust_function_creators=1;

這個動態設置的方式會在服務重啟後失效，所以我們還必須在my.cnf中設置，加上log_bin_trust_function_creators=1，這樣就會永久生效。

2：明確指明函數的類型，如果我們開啟了二進制日誌， 那麽我們就必須為我們的function指定一個參數。其中下面幾種參數類型裏面，只有 DETERMINISTIC, NO SQL 和 READS SQL DATA 被支持。這樣一來相當於明確的告知MySQL服務器這個函數不會修改數據。

1 DETERMINISTIC 不確定的

2 NO SQL 沒有SQl語句，當然也不會修改數據

3 READS SQL DATA 只是讀取數據，當然也不會修改數據

4 MODIFIES SQL DATA 要修改數據

5 CONTAINS SQL 包含了SQL語句

MySQL Err 1418 的原因分析及解決方法