第六十集 mysql高阶语句

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按关键字排序

1.1、使用ORDER BY语句来实现排序

1.2、排序可针对一个或多个字段

1.3、ASC：升序，默认排序方式

1.4、DESC：降序

1.5、ORDER BY的语法结构

语法：
 1 select column1，column2，... from 库名 order by column1,column,... asc|desc;

 1 语句使用
 2 mysql -uroot -p123123
 3 mysql> create database score;
 4 mysql> use score;
 5 mysql> create table test(xuehao int(6) not null primary key,nianling int(3) not null,xingming char(20) not null,chengji int(3) not null);
 6 mysql> insert into test values(201001,17,'zhangsan',60),(201002,17,'zhaoliu',95),(201003,18,'lisi',70),(201004,18,'wangwu',80),(201005,19,'tianqi',55);
 7 mysql> select * from test;
 8 
 9 升序
10 mysql> select chengji from test order by chengji asc;
11 +---------+
12 | chengji |
13 +---------+
14 |      55 |
15 |      60 |
16 |      70 |
17 |      80 |
18 |      95 |
19 +---------+
20 5 rows in set (0.00 sec)
21 mysql> select chengji from test order by chengji;     #默认是ASC
22 +---------+
23 | chengji |
24 +---------+
25 |      55 |
26 |      60 |
27 |      70 |
28 |      80 |
29 |      95 |
30 +---------+
31 5 rows in set (0.00 sec)
32 
33 降序
34 mysql> select chengji from test order by chengji desc;
35 +---------+
36 | chengji |
37 +---------+
38 |      95 |
39 |      80 |
40 |      70 |
41 |      60 |
42 |      55 |
43 +---------+
44 5 rows in set (0.00 sec)

按单字段排序

 1 mysql> select xuehao,xingming,chengji from test order by chengji;
 2 +--------+----------+---------+
 3 | xuehao | xingming | chengji |
 4 +--------+----------+---------+
 5 | 201005 | tianqi   |      55 |
 6 | 201001 | zhangsan |      60 |
 7 | 201003 | lisi     |      70 |
 8 | 201004 | wangwu   |      80 |
 9 | 201002 | zhaoliu  |      95 |
10 +--------+----------+---------+
11 5 rows in set (0.00 sec)

按多字段排序

 1 mysql> select xingming,chengji from test order by nianling desc,chengji desc;
 2 +----------+---------+
 3 | xingming | chengji |
 4 +----------+---------+
 5 | tianqi   |      55 |
 6 | wangwu   |      80 |
 7 | lisi     |      70 |
 8 | zhaoliu  |      95 |
 9 | zhangsan |      60 |
10 +----------+---------+
11 5 rows in set (0.00 sec)

对结果进行分组

2.1、使用GROUP BY语句来实现分组

2.2、通常结合聚合函数一起使用

2.3、可以按一个或多个字段对结果进行分组

2.4、GROUP BY分组

 1 mysql> insert into test values(201006,18,'zhangsan',80),(201007,19,'lisi',70);
 2 
 3 mysql> select * from test;                           
 4 +--------+----------+----------+---------+
 5 | xuehao | nianling | xingming | chengji |
 6 +--------+----------+----------+---------+
 7 | 201001 |       17 | zhangsan |      60 |
 8 | 201002 |       17 | zhaoliu  |      95 |
 9 | 201003 |       18 | lisi     |      70 |
10 | 201004 |       18 | wangwu   |      80 |
11 | 201005 |       19 | tianqi   |      55 |
12 | 201006 |       18 | zhangsan |      80 |
13 | 201007 |       19 | lisi     |      70 |
14 +--------+----------+----------+---------+
15 7 rows in set (0.00 sec)
16 
17 mysql> select count(xingming),nianling from test group by nianling;
18 +-----------------+----------+
19 | count(xingming) | nianling |
20 +-----------------+----------+
21 |               2 |       17 |
22 |               3 |       18 |
23 |               2 |       19 |
24 +-----------------+----------+
25 3 rows in set (0.00 sec)

GROUP BY结合ORDER BY

1 mysql> select count(xingming),nianling from test group by nianling order by nianling desc;
2 +-----------------+----------+
3 | count(xingming) | nianling |
4 +-----------------+----------+
5 |               2 |       19 |
6 |               3 |       18 |
7 |               2 |       17 |
8 +-----------------+----------+
9 3 rows in set (0.00 sec)

限制结果条目

3.1、只返回select查询结果的第一行或第几行

3.2、使用limit语句限制条目

3.3、limit语法结构

1 语法：
 2 select column1，column2，... from 库名 limit 位置偏移量 
 3 
 4 mysql> select * from test limit 3;
 5 +--------+----------+----------+---------+
 6 | xuehao | nianling | xingming | chengji |
 7 +--------+----------+----------+---------+
 8 | 201001 |       17 | zhangsan |      60 |
 9 | 201002 |       17 | zhaoliu  |      95 |
10 | 201003 |       18 | lisi     |      70 |
11 +--------+----------+----------+---------+
12 3 rows in set (0.00 sec)
13 
14 mysql> select * from test limit 3,3;
15 +--------+----------+----------+---------+
16 | xuehao | nianling | xingming | chengji |
17 +--------+----------+----------+---------+
18 | 201004 |       18 | wangwu   |      80 |
19 | 201005 |       19 | tianqi   |      55 |
20 | 201006 |       18 | zhangsan |      80 |
21 +--------+----------+----------+---------+
22 3 rows in set (0.00 sec)
23 #3，3表示从第三行开始数，显示后三行

设置别名

4.1、使用AS语句设置别名，关键字AS可省略

4.2、设置别名时，保证不能与库中其他表或字段名称冲突

4.3、别名的语法结构

1 列的别名：
 2 select 列名 as 列名别名 from 库名；
 3 表的别名：
 4 select 列名 from 库名  as 库名别名；
 5 
 6 mysql> select t.xuehao as 学号,t.nianling as 年龄,t.xingming as 姓名,t.chengji as 成绩 from test as t;
 7 +--------+--------+----------+--------+
 8 | 学号   | 年龄   | 姓名     | 成绩   |
 9 +--------+--------+----------+--------+
10 | 201001 |     17 | zhangsan |     60 |
11 | 201002 |     17 | zhaoliu  |     95 |
12 | 201003 |     18 | lisi     |     70 |
13 | 201004 |     18 | wangwu   |     80 |
14 | 201005 |     19 | tianqi   |     55 |
15 | 201006 |     18 | zhangsan |     80 |
16 | 201007 |     19 | lisi     |     70 |
17 +--------+--------+----------+--------+
18 7 rows in set (0.00 sec)

as作为连接语句

 1 mysql> create table test1 as select * from test;
 2 
 3 mysql> select * from test1;
 4 +--------+----------+----------+---------+
 5 | xuehao | nianling | xingming | chengji |
 6 +--------+----------+----------+---------+
 7 | 201001 |       17 | zhangsan |      60 |
 8 | 201002 |       17 | zhaoliu  |      95 |
 9 | 201003 |       18 | lisi     |      70 |
10 | 201004 |       18 | wangwu   |      80 |
11 | 201005 |       19 | tianqi   |      55 |
12 | 201006 |       18 | zhangsan |      80 |
13 | 201007 |       19 | lisi     |      70 |
14 +--------+----------+----------+---------+
15 7 rows in set (0.00 sec)

通配符的使用

5.1、用于替换字符串中的部分字符

5.2、通常配合like一起使用，并协同where完成查询

5.3、常用通配符

5.3.1、%：表示0个，1个或多个

5.3.2、_：表示单个字符

 1 mysql> select xuehao,xingming from test where xingming like 'z%';
 2 +--------+----------+
 3 | xuehao | xingming |
 4 +--------+----------+
 5 | 201001 | zhangsan |
 6 | 201002 | zhaoliu  |
 7 | 201006 | zhangsan |
 8 +--------+----------+
 9 3 rows in set (0.00 sec)
10 
11 mysql> select xuehao,xingming from test where xingming like 'lis_';
12 +--------+----------+
13 | xuehao | xingming |
14 +--------+----------+
15 | 201003 | lisi     |
16 | 201007 | lisi     |
17 +--------+----------+
18 2 rows in set (0.00 sec)

子查询

6.1、也称作内查询或者嵌套查询

6.2、先于主查询被执行，其结果将作为外层查询的条件

6.3、在增删改查中都可以使用子查询

6.4、支持多层嵌套

6.5、IN语句是用来判断某个值是否在给定的结果集中

6.6、子查询的用法

1 查询：
 2 mysql> select xuehao as 学号,chengji as 成绩 from test where chengji in (select chengji from test where chengji >=60);
 3 +--------+--------+
 4 | 学号   | 成绩   |
 5 +--------+--------+
 6 | 201001 |     60 |
 7 | 201002 |     95 |
 8 | 201003 |     70 |
 9 | 201007 |     70 |
10 | 201004 |     80 |
11 | 201006 |     80 |
12 +--------+--------+
13 6 rows in set (0.00 sec)
14 
15 查询结合降序使用：
16 mysql> select xuehao as 学号,chengji as 成绩 from test where chengji in (select chengji from test where chengji >=60) order by chengji desc;
17 +--------+--------+
18 | 学号   | 成绩   |
19 +--------+--------+
20 | 201002 |     95 |
21 | 201004 |     80 |
22 | 201006 |     80 |
23 | 201007 |     70 |
24 | 201003 |     70 |
25 | 201001 |     60 |
26 +--------+--------+
27 6 rows in set (0.01 sec)
28 
29 插入：
30 mysql> create table test_ as select * from score;
31 mysql> delete from test_;
32 mysql> select * from test_;
33 mysql> insert into test_ select * from test where chengji in (select chengji from test where chengji >=80);
34 mysql> select * from test_;
35 +--------+----------+----------+---------+
36 | xuehao | nianling | xingming | chengji |
37 +--------+----------+----------+---------+
38 | 201002 |       17 | zhaoliu  |      95 |
39 | 201004 |       18 | wangwu   |      80 |
40 | 201006 |       18 | zhangsan |      80 |
41 +--------+----------+----------+---------+
42 3 rows in set (0.00 sec)
43 
44 修改：、
45 mysql> alter table test_ add column num int(3);
46 mysql> desc test_ ;
47 mysql> update test_ set num=101 where chengji in (select chengji from test where chengji >=80);
48 mysql> select * from test_;
49 +--------+----------+----------+---------+------+
50 | xuehao | nianling | xingming | chengji | num  |
51 +--------+----------+----------+---------+------+
52 | 201002 |       17 | zhaoliu  |      95 |  101 |
53 | 201004 |       18 | wangwu   |      80 |  101 |
54 | 201006 |       18 | zhangsan |      80 |  101 |
55 +--------+----------+----------+---------+------+
56 3 rows in set (0.00 sec)
57 
58 删除：
59 mysql> delete from test where chengji in(select chengji from (select *from test where chengji >=75)a);
60 mysql> select * from test;
61 +--------+----------+----------+---------+
62 | xuehao | nianling | xingming | chengji |
63 +--------+----------+----------+---------+
64 | 201001 |       17 | zhangsan |      60 |
65 | 201003 |       18 | lisi     |      70 |
66 | 201005 |       19 | tianqi   |      55 |
67 | 201007 |       19 | lisi     |      70 |
68 +--------+----------+----------+---------+
69 4 rows in set (0.00 sec)

NULL值

7.1、表示缺失的值

7.2、与数字0或者空白（spaces）是不同的

7.3、使用IS NULL或IS NOT NULL进行判断

7.4、NULL值和空值的区别

7.4.1、空值长度为0，不占空间；NULL值的长度为NULL，占用空间

7.4.2、IS NULL无法判断空值

7.4.3、空值使用“=”或者“<>”来处理

7.4.4、COUNT（）计算时，NULL会忽略，空值会加入计算

 1 插入空值：
 2 mysql> alter table test_ add column class varchar(16);
 3 mysql> select * from test_;
 4 mysql> insert into test_ values(201007,19,'lisi',80,102,'');
 5 mysql> select * from test_;
 6 +--------+----------+----------+---------+------+-------+
 7 | xuehao | nianling | xingming | chengji | num  | class |
 8 +--------+----------+----------+---------+------+-------+
 9 | 201002 |       17 | zhaoliu  |      95 |  101 | NULL  |
10 | 201004 |       18 | wangwu   |      80 |  101 | NULL  |
11 | 201006 |       18 | zhangsan |      80 |  101 | NULL  |
12 | 201007 |       19 | lisi     |      80 |  102 |       |
13 +--------+----------+----------+---------+------+-------+
14 
15 null的用法：
16 mysql> select * from test_ where class is null ;
17 +--------+----------+----------+---------+------+-------+
18 | xuehao | nianling | xingming | chengji | num  | class |
19 +--------+----------+----------+---------+------+-------+
20 | 201002 |       17 | zhaoliu  |      95 |  101 | NULL  |
21 | 201004 |       18 | wangwu   |      80 |  101 | NULL  |
22 | 201006 |       18 | zhangsan |      80 |  101 | NULL  |
23 +--------+----------+----------+---------+------+-------+
24 3 rows in set (0.00 sec)
25 mysql> select * from test_ where class is not null;
26 +--------+----------+----------+---------+------+-------+
27 | xuehao | nianling | xingming | chengji | num  | class |
28 +--------+----------+----------+---------+------+-------+
29 | 201007 |       19 | lisi     |      80 |  102 |       |
30 +--------+----------+----------+---------+------+-------+
31 1 row in set (0.00 sec)

正则表达式

8.1、根据指定的匹配模式匹配记录中符合要求的特殊字符

8.2、使用REGEXP关键字指定匹配模式

8.3、常用匹配模式

字符	说明
^	匹配开始字符
$	匹配结束字符
.	匹配任意单个字符
*	匹配任意个前面的字符
+	匹配前面字符至少1次
p1或p2	匹配p1或p2
[…]	匹配字符集中括号内的任何字符
[^…]	匹配不在括号内的任何字符
{n}	匹配前面的字符串n次
{n,m}	匹配前面的字符串至少n次，至多m次

 1 以z开头的姓名：(^)
 2 mysql> select xuehao,xingming,chengji from test_ where xingming regexp '^z';
 3 +--------+----------+---------+
 4 | xuehao | xingming | chengji |
 5 +--------+----------+---------+
 6 | 201002 | zhaoliu  |      95 |
 7 | 201006 | zhangsan |      80 |
 8 +--------+----------+---------+
 9 2 rows in set (0.00 sec)
10 
11 以n结尾的姓名：($)
12 mysql> select xuehao,xingming,chengji from test_ where xingming regexp 'n$';
13 +--------+----------+---------+
14 | xuehao | xingming | chengji |
15 +--------+----------+---------+
16 | 201006 | zhangsan |      80 |
17 +--------+----------+---------+
18 1 row in set (0.00 sec)
19 
20 匹配单个字符（.）
21 mysql> select xuehao,xingming,chengji from test_ where xingming regexp 'lis.';
22 +--------+----------+---------+
23 | xuehao | xingming | chengji |
24 +--------+----------+---------+
25 | 201007 | lisi     |      80 |
26 +--------+----------+---------+
27 1 row in set (0.00 sec)
28 
29 匹配前面字符至少1次（+）
30 mysql> insert into test_ values(201008,20,'lio',75,103,''),(201009,20,'lioo',85,104,''),(201009,20,'liooo',55,105,'');
31 mysql> select xuehao,xingming,chengji from test_ where xingming regexp 'lioo+';
32 +--------+----------+---------+
33 | xuehao | xingming | chengji |
34 +--------+----------+---------+
35 | 201009 | lioo     |      85 |
36 | 201009 | liooo    |      55 |
37 +--------+----------+---------+
38 2 rows in set (0.00 sec)
39 
40 匹配任意个前面的字符(*)
41 mysql> select xuehao,xingming,chengji from test_ where xingming regexp 'lio*';
42 +--------+----------+---------+
43 | xuehao | xingming | chengji |
44 +--------+----------+---------+
45 | 201002 | zhaoliu  |      95 |
46 | 201007 | lisi     |      80 |
47 | 201008 | lio      |      75 |
48 | 201009 | lioo     |      85 |
49 | 201009 | liooo    |      55 |
50 +--------+----------+---------+
51 5 rows in set (0.00 sec)
52 
53 匹配p1或p2(p1|p2)
54 mysql> select xuehao,xingming,chengji from test_ where xingming regexp 'l|n';
55 +--------+----------+---------+
56 | xuehao | xingming | chengji |
57 +--------+----------+---------+
58 | 201002 | zhaoliu  |      95 |
59 | 201004 | wangwu   |      80 |
60 | 201006 | zhangsan |      80 |
61 | 201007 | lisi     |      80 |
62 | 201008 | lio      |      75 |
63 | 201009 | lioo     |      85 |
64 | 201009 | liooo    |      55 |
65 +--------+----------+---------+
66 7 rows in set (0.00 sec)
67 
68 匹配字符集中括号内的任何字符([...])
69 mysql> select xuehao,xingming,chengji from test_ where xingming regexp '[hz]';
70 +--------+----------+---------+
71 | xuehao | xingming | chengji |
72 +--------+----------+---------+
73 | 201002 | zhaoliu  |      95 |
74 | 201006 | zhangsan |      80 |
75 +--------+----------+---------+
76 2 rows in set (0.00 sec)
77 
78 匹配前面的字符串n次{n}
79 mysql> select xuehao,xingming,chengji from test_ where xingming regexp 'o{2}';
80 +--------+----------+---------+
81 | xuehao | xingming | chengji |
82 +--------+----------+---------+
83 | 201009 | lioo     |      85 |
84 | 201009 | liooo    |      55 |
85 +--------+----------+---------+
86 2 rows in set (0.00 sec)
87 
88 匹配前面的字符串至少n次，至多m次({n,m})
89 mysql> select xuehao,xingming,chengji from test_ where xingming regexp 'o{2,3}';
90 +--------+----------+---------+
91 | xuehao | xingming | chengji |
92 +--------+----------+---------+
93 | 201009 | lioo     |      85 |
94 | 201009 | liooo    |      55 |
95 +--------+----------+---------+
96 2 rows in set (0.00 sec)

算术运算符

9.1、MySQL支持的算术运算符

字符	说明
+	加法
-	减法
*	乘法
/	除法
%	取余数

mysql> select 5+2 as addition,8-5 as subtraction,6*7 as multiplication,8/2 as division,9%4 as remainder;
2 +----------+-------------+----------------+----------+-----------+
3 | addition | subtraction | multiplication | division | remainder |
4 +----------+-------------+----------------+----------+-----------+
5 |        7 |           3 |             42 |   4.0000 |         1 |
6 +----------+-------------+----------------+----------+-----------+
7 1 row in set (0.00 sec)

9.2、比较运算符

9.2.1、字符串的比较默认不区分大小写，可使用binary来区分

9.2.2、常用比较运算符

运算符	说明
=	等于
>	大于
<	小于
>=	大于或等于
<=	小于或等于
!=或<>	不等于
IN	在集合中
LIKE	通配符匹配
IS NULL	判断一个值是否为NULL
IS NOT NULL	判断一个值是否不为NULL
BETWEEN AND	两者之间
GREATEST	两个或多个参数时返回最大值
LEAST	两个或多个参数时返回最小值

1 mysql> select 2=4,2='2','e'='e',(4+4)=(5+3),'n'=NULL;
2 +-----+-------+---------+-------------+----------+
3 | 2=4 | 2='2' | 'e'='e' | (4+4)=(5+3) | 'n'=NULL |
4 +-----+-------+---------+-------------+----------+
5 |   0 |     1 |       1 |           1 |     NULL |
6 +-----+-------+---------+-------------+----------+
7 1 row in set (0.01 sec)

从以上查询可以看出：

①如果两者都是整数，则按整数值进行比较

②如果一个整数一个字符串，则会自动将字符串转换为数字，再进行比较

③如果两者都是字符串，则按照字符串进行比较

④如果两者中至少有一个值是NULL，则比较的结果是NULL。

 1 mysql> select 2>4,2<'2', 'e'>='e',(4+4)<=(5+3);
 2 +-----+-------+----------+--------------+
 3 | 2>4 | 2<'2' | 'e'>='e' | (4+4)<=(5+3) |
 4 +-----+-------+----------+--------------+
 5 |   0 |     0 |        1 |            1 |
 6 +-----+-------+----------+--------------+
 7 1 row in set (0.00 sec)
 8 
 9 mysql> select 2!=4,null is null,null is not null,2 between 1 and 4;
10 +------+--------------+------------------+-------------------+
11 | 2!=4 | null is null | null is not null | 2 between 1 and 4 |
12 +------+--------------+------------------+-------------------+
13 |    1 |            1 |                0 |                 1 |
14 +------+--------------+------------------+-------------------+
15 1 row in set (0.00 sec)
16 
17 mysql> select greatest (5,8,12),least (1,5,4);
18 +-------------------+---------------+
19 | greatest (5,8,12) | least (1,5,4) |
20 +-------------------+---------------+
21 |                12 |             1 |
22 +-------------------+---------------+
23 1 row in set (0.00 sec)

逻辑运算符
10.1、又称为布尔运算符

10.2、用来判断表达式的真假

10.3、常用的逻辑运算符

运算符	说明
NOT或！	逻辑非
AND或&&	逻辑与
OR	逻辑或
XOR	逻辑异或

 1 逻辑非
 2 mysql> select not 2,!3,not 0,!(4-4);
 3 +-------+----+-------+--------+
 4 | not 2 | !3 | not 0 | !(4-4) |
 5 +-------+----+-------+--------+
 6 |     0 |  0 |     1 |      1 |
 7 +-------+----+-------+--------+
 8 1 row in set (0.00 sec)
 9 
10 逻辑与
11 mysql> select 2 and 3,4 && 0,0 && NULL,1 and NULL;
12 +---------+--------+-----------+------------+
13 | 2 and 3 | 4 && 0 | 0 && NULL | 1 and NULL |
14 +---------+--------+-----------+------------+
15 |       1 |      0 |         0 |       NULL |
16 +---------+--------+-----------+------------+
17 1 row in set (0.00 sec)

连接查询

    MySQL的连接查询，通常都是将来自两个或多个表的行结合起来，基于这些表之间的共同字段，进行数据的拼接，首先，要确定一个主表作为结果集，然后将其他表的行有选择性的连接到选定的主表结果集上，使用较多的连接查询包括：内连接、左连接和右连接

1 mysql> select t.xuehao,t.xingming,t.chengji from test_ t inner join test t1 on t.xingming=t1.xingming;
2 +--------+----------+---------+
3 | xuehao | xingming | chengji |
4 +--------+----------+---------+
5 | 201006 | zhangsan |      80 |
6 | 201007 | lisi     |      80 |
7 | 201007 | lisi     |      80 |
8 +--------+----------+---------+
9 3 rows in set (0.00 sec)

函数

13.1、数学函数

函数	含义
abs(x)	返回x的绝对值
rand()	返回0到1的随机数
mod(x,y)	返回x除以y以后的余数
power(x,y)	返回x的y次方
round(x)	返回离x最近的整数
round(x,y)	保留x的y位小数四舍五入后的值
sqrt(x)	返回x的平方根
truncate(x,y)	返回数字x截断为y位小树的值
ceil(x)	返回大于或等于x的最小整数
floor(x)	返回小于或等于x的最大整数
greatest(x1,x2…)	返回集合中最大的值
least(x1,x2…)	返回集合中最小的值

常用的数学函数举例说明
 1 mysql> select abs(-12),rand(),rand(),mod(4,5),power(2,6);
 2 +----------+--------------------+--------------------+----------+------------+
 3 | abs(-12) | rand()             | rand()             | mod(4,5) | power(2,6) |
 4 +----------+--------------------+--------------------+----------+------------+
 5 |       12 | 0.7755411516647238 | 0.7329282013074757 |        4 |         64 |
 6 +----------+--------------------+--------------------+----------+------------+
 7 1 row in set (0.00 sec)
 8 
 9 mysql> select round(2.4),round(2.5),round(2.4235,2),sqrt(2),truncate(2.4652,2);
10 +------------+------------+-----------------+--------------------+--------------------+
11 | round(2.4) | round(2.5) | round(2.4235,2) | sqrt(2)            | truncate(2.4652,2) |
12 +------------+------------+-----------------+--------------------+--------------------+
13 |          2 |          3 |            2.42 | 1.4142135623730951 |               2.46 |
14 +------------+------------+-----------------+--------------------+--------------------+
15 1 row in set (0.00 sec)
16 
17 mysql> select ceil(2.2),floor(2.8),greatest(1,2,3,4,5),least(1,2,3,4,5);
18 +-----------+------------+---------------------+------------------+
19 | ceil(2.2) | floor(2.8) | greatest(1,2,3,4,5) | least(1,2,3,4,5) |
20 +-----------+------------+---------------------+------------------+
21 |         3 |          2 |                   5 |                1 |
22 +-----------+------------+---------------------+------------------+
23 1 row in set (0.00 sec)