insert into passengerpidpnamecardnumsexusernamephoneVALUESnull王2010663198902156699女A518902156699;insert into passengerpidpnamecardnumsexusernamephoneVALUESnull宋5010663200001011111女A318901011111;insert

1）查询不重复的旅客名和身份证号： SELECT DISTINCT pname, cardnum FROM passenger;

2）查询有多少个不重复的旅客名和身份证号： SELECT COUNT(DISTINCT pname, cardnum) FROM passenger;

3）查询有多少个姓张的旅客： SELECT COUNT(*) FROM passenger WHERE pname LIKE '张%';

4）将不重复的旅客信息全部查询出来（旅客名、身份证号、手机号、性别）： SELECT DISTINCT pname, cardnum, phone, sex FROM passenger;

5）查询有多少个不重复的username账号： SELECT COUNT(DISTINCT username) FROM passenger;

6）查询每个账号下有多个旅客： SELECT username, COUNT(*) FROM passenger GROUP BY username;