- 分頁查詢
# 查詢前五條數據作爲第一頁
select * from student limit 0,5
# 先排序再分頁
select * from student order by Gid DESC,Sid ASC limit 0,5
- 求平均值
# 求Sid字段的平均值
select avg(Sid) from student
# 以Gid爲基礎分組,再求每組Sid的平均值
select avg(Sid) from student group by Gid
- 求最大值
# 求Sid字段的最大值
select max(Sid) from student
# 以Gid爲基礎分組,再求每組Sid的最值
select max(Sid) from student group by Gid
- 求最小值
# 求Sid字段的最小值
select min(Sid) from student
# 以Gid爲基礎分組,再求每組Sid的最小值
select min(Sid) from student group by Gid
- 求和
# 求Sid字段的和值
select sum(Sid) from student
# 以Gid爲基礎分組,再求每組Sid的和值
select sum(Sid) from student group by Gid
- 求總記錄數
# 求數據表中有多少行數據。其中Sid不能是null值,如果不能確定那個字段是null可以用 *
select count(Sid) from student
# 以Gid爲基礎分組,再求每組有多少行
select count(Sid) from student group by Gid