mysql -查询练习2
select 18/5;
select 18%5;
select DEGREES(PI()/4);
select pow(9,4);
select round(3.14159,2);
select length("Hello World!");
select length("University");
select substring("nice to meet you",9,4);
select repeat("Cheer",3);
select reverse("voodoo");
select concat_ws(" ","MySql","is","great");
select week('2017-11-13',1);
select dayofweek('2017-11-14');
select timestampdiff(year,'1929-02-14','2017-11-14');
select date_format('2017-11-14','%y %a %D %W');
select second(curtime());
show processlist;
select encode("mysql","ha");
select decode(encode("mysql","ha"),"ha");
SELECT HEX(100);
select format("5.1584",3);
select convert("new string" using "gb2312");
mysql> select 18/5;
+--------+
| 18/5 |
+--------+
| 3.6000 |
+--------+
1 row in set (0.00 sec)
mysql> select 18%5;
+------+
| 18%5 |
+------+
| 3 |
+------+
1 row in set (0.00 sec)
mysql> select DEGREES(PI()/4);
+-----------------+
| DEGREES(PI()/4) |
+-----------------+
| 45 |
+-----------------+
1 row in set (0.00 sec)
mysql> select pow(9,4);
+----------+
| pow(9,4) |
+----------+
| 6561 |
+----------+
1 row in set (0.00 sec)
mysql> select round(3.14159,2);
+------------------+
| round(3.14159,2) |
+------------------+
| 3.14 |
+------------------+
1 row in set (0.00 sec)
mysql>
mysql> select length("Hello World!");
+------------------------+
| length("Hello World!") |
+------------------------+
| 12 |
+------------------------+
1 row in set (0.00 sec)
mysql> select length("University");
+----------------------+
| length("University") |
+----------------------+
| 10 |
+----------------------+
1 row in set (0.00 sec)
mysql> select substring("nice to meet you",9,4);
+-----------------------------------+
| substring("nice to meet you",9,4) |
+-----------------------------------+
| meet |
+-----------------------------------+
1 row in set (0.00 sec)
mysql> select repeat("Cheer",3);
+-------------------+
| repeat("Cheer",3) |
+-------------------+
| CheerCheerCheer |
+-------------------+
1 row in set (0.00 sec)
mysql> select reverse("voodoo");
+-------------------+
| reverse("voodoo") |
+-------------------+
| oodoov |
+-------------------+
1 row in set (0.00 sec)
mysql> select concat_ws(" ","MySql","is","great");
+-------------------------------------+
| concat_ws(" ","MySql","is","great") |
+-------------------------------------+
| MySql is great |
+-------------------------------------+
1 row in set (0.00 sec)
mysql>
mysql> select week('2017-11-13',1);
+----------------------+
| week('2017-11-13',1) |
+----------------------+
| 46 |
+----------------------+
1 row in set (0.00 sec)
mysql> select dayofweek('2017-11-14');
+-------------------------+
| dayofweek('2017-11-14') |
+-------------------------+
| 3 |
+-------------------------+
1 row in set (0.00 sec)
mysql> select timestampdiff(year,'1929-02-14','2017-11-14');
+-----------------------------------------------+
| timestampdiff(year,'1929-02-14','2017-11-14') |
+-----------------------------------------------+
| 88 |
+-----------------------------------------------+
1 row in set (0.00 sec)
mysql> select date_format('2017-11-14','%y %a %D %W');
+-----------------------------------------+
| date_format('2017-11-14','%y %a %D %W') |
+-----------------------------------------+
| 17 Tue 14th Tuesday |
+-----------------------------------------+
1 row in set (0.00 sec)
mysql> select second(curtime());
+-------------------+
| second(curtime()) |
+-------------------+
| 26 |
+-------------------+
1 row in set (0.00 sec)
mysql>
mysql> show processlist;
+-----+------+-----------+------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+-----+------+-----------+------+---------+------+-------+------------------+
| 612 | root | localhost | NULL | Sleep | 8843 | | NULL |
| 616 | root | localhost | NULL | Query | 0 | init | show processlist |
+-----+------+-----------+------+---------+------+-------+------------------+
2 rows in set (0.00 sec)
mysql> select encode("mysql","ha");
+----------------------+
| encode("mysql","ha") |
+----------------------+
| 4?S? |
+----------------------+
1 row in set (0.00 sec)
mysql> select decode(encode("mysql","ha"),"ha");
+-----------------------------------+
| decode(encode("mysql","ha"),"ha") |
+-----------------------------------+
| mysql |
+-----------------------------------+
1 row in set (0.00 sec)
mysql> SELECT HEX(100);
+----------+
| HEX(100) |
+----------+
| 64 |
+----------+
1 row in set (0.00 sec)
mysql> select format("5.1584",3);
+--------------------+
| format("5.1584",3) |
+--------------------+
| 5.158 |
+--------------------+
1 row in set (0.00 sec)
mysql> select convert("new string" using "gb2312");