查询两张表的所有数据
SELECT * FROM 表A union UNION ALL SELECT * FROM 表B
UNION在进行表链接后会筛选掉重复的记录,Union All不会去除重复记
一般情况下要保证 表A 和表B 字段数 并且字段类型要一样,
如果你要查的 两张表中 大部分 相同 但仍有不同字段,但是又需要同时查到两张表的数据则可以利用别名处理
例:
表A : studentName ,teacherName,schoolName
表B: studentName,className,studentSex
则sql:SELECT studentName,teacherName,schoolName," " AS className," " AS studentSex FROM 表A
UNION ALL SELECT studnetName," " AS teacherName," " AS schoolName,className,studentSex FROM 表 B
这样就可以查出两张表的所有数据了