UNION 操作
語法:SELECT * FROM 表名1 UNION ALL SELECT * FROM 表名2
UNION 操作要保證兩個表或者多個表的列數要相同(看列子)
例子:SELECT * FROM student UNION ALL SELECT * FROM Course
UNION 操作
語法:SELECT * FROM 表名1 UNION ALL SELECT * FROM 表名2
UNION 操作要保證兩個表或者多個表的列數要相同(看列子)
例子:SELECT * FROM student UNION ALL SELECT * FROM Course