数据库编程细节问题 -- 获取关于mysql的基本信息

# 数据库相关的基本操作，获取关于数据库的信息use mysql;SELECT host,user from user;GRANT ALL on app_detail to root;SELECT * FROM permission;#去掉主键。alter table apk_info_wang DROP PRIMARY key;alter TABLE method_info_wang DROP PRIMARY KEY;#修改模式ALTER table apk_info_wang add apk_id BIGINT not null PRIMARY KEY;alter table apk_info_wang change apk_id apk_id bigint not null auto_increment = 1;#显示相关信息show DATABASES;show TABLES;show COLUMNS from apk_info_wang; # 测试基本状态EXPLAIN SELECT * FROM call_info_wang; EXPLAIN SELECT call_info_wang.calleeApkName,call_info_wang.calleeApkVersion FROM call_info_wang WHEREcalleeApkName in (SELECT apk_info_wang.apkName FROM apk_info_wang);       EXPLAIN SELECT call_info_wang.calleeApkName,call_info_wang.calleeApkVersion FROM call_info_wang WHEREcall_info_wang.callerPackageName in (SELECT package_info_wang.packageName FROM package_info_wang);