摘要： 1) show databases;2) use db; 进入到数据库db3) select database(); --显示当前数据库4) select "consstr" as colname, t.* from tableName t;5) select a.id,a.valueA, case (b.valueB is NULL) when 1 then 'z' else b.valueB end from tableA as a left join tableB as b on(id);6)导入.sql脚本： 在命令行下：mysql -h *** - 阅读全文