問題1：
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 35
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 35
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 35
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
130305 19:49:08 InnoDB: Unable to open the first data file
InnoDB: Error in opening ./ibdata1
130305 19:49:08 InnoDB: Operating system error number 35 in a file operation.此問題的關鍵在於：
Check that you do not already have another mysqld process表示有多個mysql進程正在執行，解決方法如下：
1、打開終端，輸入$ ps aux | grep mysqld 檢查mysql進程打開終端，輸入$ ps aux | grep mysqld 檢查mysql進程
比如：$ kill 1234（此處1234 爲你的進程號）
然後就可以正常使用你的mysql 了。
問題2：
2017-07-31 10:37:08 12746 [Note] Plugin 'FEDERATED' is disabled.
2017-07-31 10:37:08 12746 [Note] InnoDB: Using atomics to ref count buffer pool pages
2017-07-31 10:37:08 12746 [Note] InnoDB: The InnoDB memory heap is disabled
2017-07-31 10:37:08 12746 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2017-07-31 10:37:08 12746 [Note] InnoDB: Memory barrier is not used
2017-07-31 10:37:08 12746 [Note] InnoDB: Compressed tables use zlib 1.2.8
2017-07-31 10:37:08 12746 [Note] InnoDB: Using CPU crc32 instructions
2017-07-31 10:37:08 12746 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2017-07-31 10:37:08 12746 [Note] InnoDB: Completed initialization of buffer pool
2017-07-31 10:37:08 12746 [Note] InnoDB: Highest supported file format is Barracuda.
2017-07-31 10:37:08 12746 [Note] InnoDB: The log sequence numbers 1638988 and 1638988 in ibdata files do not match the log sequence number 1644885 in the ib_logfiles!
2017-07-31 10:37:08 12746 [Note] InnoDB: Database was not shutdown normally!
2017-07-31 10:37:08 12746 [Note] InnoDB: Starting crash recovery.
2017-07-31 10:37:08 12746 [Note] InnoDB: Reading tablespace information from the .ibd files...
2017-07-31 10:37:08 12746 [ERROR] InnoDB: Attempted to open a previously opened tablespace. Previous tablespace info/test uses space ID: 3 at filepath: ./info/test.ibd. Cannot open tablespace mysql/slave_relay_log_info which uses space ID: 3 at filepath: ./mysql/slave_relay_log_info.ibd
2017-07-31 10:37:08 7ffff2e8f3c0 InnoDB: Operating system error number 2 in a file operation.
InnoDB: The error means the system cannot find the path specified.
InnoDB: If you are installing InnoDB, remember that you must create
InnoDB: directories yourself, InnoDB does not create them.
InnoDB: Error: could not open single-table tablespace file ./mysql/slave_relay_log_info.ibd
InnoDB: We do not continue the crash recovery, because the table may become
InnoDB: corrupt if we cannot apply the log records in the InnoDB log to it.
InnoDB: To fix the problem and start mysqld:
InnoDB: 1) If there is a permission problem in the file and mysqld cannot
InnoDB: open the file, you should modify the permissions.
InnoDB: 2) If the table is not needed, or you can restore it from a backup,
InnoDB: then you can remove the .ibd file, and InnoDB will do a normal
InnoDB: crash recovery and ignore that table.
InnoDB: 3) If the file system or the disk is broken, and you cannot remove
InnoDB: the .ibd file, you can set innodb_force_recovery > 0 in my.cnf
InnoDB: and force InnoDB to continue crash recovery here.此問題的關鍵在於：
InnoDB: Attempted to open a previously opened tablespace. Previous tablespace db_patients/tb_patients uses space ID: 3 at filepath: ./db_patients/tb_patients.ibd. Cannot open tablespace mysql/slave_relay_log_info which uses space ID: 3 at filepath: ./mysql/slave_relay_log_info.ibd解決辦法：
一、打開MAMP PRO，選擇菜單欄File->Edit Template->MySQL->5.5.3（選擇你的版本）），這時打開了一個文本，找到
[mysqld]注意帶上中括號，在這行下面加一行
innodb_force_recovery = 1 （可換1-6 進行嘗試）
二、啓動mySQL，成功後再關閉；
三、重新打開那個文本，刪除添加的 innodb_force_recovery = 1 行；
四、再打開mySQL，完畢。