記錄學習MySQL過程中遇到並處理過的一些異常——持續更新
1.MySQL安裝報錯(博文http://blog.csdn.net/hwhmh2010/article/details/52984890中遇到的報錯)
***** Installing MySQL...******
CMake Error: The source directory "/root/soft/mysql-5.6.25-linux-glibc2.5-x86_64" does not appear to contain CMakeLists.txt.
Specify --help for usage, or press the help button on the CMake GUI.
execute command ==> make && make install
make: *** No targets specified and no makefile found. Stop.
原因：安裝包下載地址錯誤，重新 更新下面兩個下載地址的參數變量
WEBSITEPATH=http://downloads.mysql.com/archives/get/file/ 改爲 WEBSITEPATH=http://downloads.mysql.com/archives/get/file/
SOFTEDITION=mysql-5.6.25-linux-glibc2.5-x86_64 改爲 SOFTEDITION=mysql-5.6.25
2.truncate表報錯
[SQL]
truncate table s_department;
[Err] 1701 - Cannot truncate a table referenced in a foreign key constraint (`dba_test_abc`.`s_user`, CONSTRAINT `FK_jdi1gsiep4tepn7f2p95cigq2` FOREIGN KEY (`dept`) REFERENCES `dba_test_abc`.`s_department` (`code`))
原因：MySQL主外鍵關係的表，不允許truncate，此例中s_user.dept列對s_department.code列有外鍵依賴
查看錶之間關係：
select distinct TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME,REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME from information_schema.KEY_COLUMN_USAGE where REFERENCED_TABLE_NAME <>'' and REFERENCED_COLUMN_NAME='code'
查看錶結構(結果略)：
show create table s_department;
show create table s_user;
處理方法：
1.先SET FOREIGN_KEY_CHECKS=0 然後truncate table，再SET FOREIGN_KEY_CHECKS=1
2.先備份數據庫和表之間的外鍵關係，然後刪除外鍵，再truncate，最後添加外鍵關係
ALTER TABLE dba_test_abc.s_user DROP FOREIGN KEY FK_jdi1gsiep4tepn7f2p95cigq2;
ALTER TABLE s_user ADD CONSTRAINT FK_jdi1gsiep4tepn7f2p95cigq2 FOREIGN KEY(dept) REFERENCES s_department(code);
3.如果表中數據不多，可直接delete替代truncate（注：delete會產生遠遠大於truncate的事務日誌，如果表巨大，此法不可取）
