MySQL ERROR 1005 (HY000): Can't create table 'schema_name.table_name' (errno: 150)

今天在按照书上的例子学习Yii的时候发现在创建一个有外键的MySQL表的时候总是报以下错误

ERROR 1005 (HY000): Can't create table '<schema>.<table>' (errno: 150)

但是仅仅从这个错误消息根本得不到任何对排查错误有意义的信息，找了一些文章大多数是说外键表和原表里声明的字段类型不一致，但是都没有给出怎么查出是这个错误的，后来发现原来可以通过运行"SHOW ENGINE INNODB STATUS;"命令，然后在命令结果中的“LATEST FOREIGN KEY ERROR”部分得到具体的错误消息。如下：

...mysql> SHOW ENGINE INNODB STATUS\G*************************** 1. row ***************************  Type: InnoDB  Name: Status: =====================================110920 23:26:39 INNODB MONITOR OUTPUT=====================================Per second averages calculated from the last 19 seconds----------SEMAPHORES----------OS WAIT ARRAY INFO: reservation count 46, signal count 46Mutex spin waits 0, rounds 260, OS waits 13RW-shared spins 58, OS waits 29; RW-excl spins 5, OS waits 4------------------------LATEST FOREIGN KEY ERROR------------------------110920 23:26:33 Error in foreign key constraint of table trackstar_test/tbl_project_user_role:foreign key (`project_id`) references `tbl_project` (`id`) on delete cascade on update cascade) engine InnoDB:Cannot resolve table name close to: (`id`) on delete cascade on update cascade) engine InnoDB------------TRANSACTIONS------------Trx id counter 0 6375Purge done for trx's n:o < 0 6353 undo n:o < 0 0History list length 13LIST OF TRANSACTIONS FOR EACH SESSION:---TRANSACTION 0 0, not started, process no 755, OS thread id 2991618928MySQL thread id 42, query id 383 localhost rootSHOW ENGINE INNODB STATUS--------FILE I/O--------I/O thread 0 state: waiting for i/o request (insert buffer thread)I/O thread 1 state: waiting for i/o request (log thread)I/O thread 2 state: waiting for i/o request (read thread)I/O thread 3 state: waiting for i/o request (write thread)Pending normal aio reads: 0, aio writes: 0, ibuf aio reads: 0, log i/o's: 0, sync i/o's: 0Pending flushes (fsync) log: 0; buffer pool: 036 OS file reads, 281 OS file writes, 177 OS fsyncs0.00 reads/s, 0 avg bytes/read, 0.05 writes/s, 0.05 fsyncs/s-------------------------------------INSERT BUFFER AND ADAPTIVE HASH INDEX-------------------------------------Ibuf: size 1, free list len 0, seg size 2,0 inserts, 0 merged recs, 0 mergesHash table size 34679, node heap has 1 buffer(s)0.00 hash searches/s, 1.16 non-hash searches/s---LOG---Log sequence number 0 1774918Log flushed up to   0 1774918Last checkpoint at  0 17727960 pending log writes, 0 pending chkp writes128 log i/o's done, 0.05 log i/o's/second----------------------BUFFER POOL AND MEMORY----------------------Total memory allocated 17596386; in additional pool allocated 960512Dictionary memory allocated 58096Buffer pool size   512Free buffers       468Database pages     43Modified db pages  10Pending reads 0Pending writes: LRU 0, flush list 0, single page 0Pages read 35, created 8, written 2960.00 reads/s, 0.00 creates/s, 0.00 writes/sBuffer pool hit rate 1000 / 1000--------------ROW OPERATIONS--------------0 queries inside InnoDB, 0 queries in queue1 read views open inside InnoDBMain thread process no. 755, id 2955570032, state: sleepingNumber of rows inserted 60, updated 0, deleted 0, read 1590.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s----------------------------END OF INNODB MONITOR OUTPUT============================