mysql使用06

本文主要是介绍mysql使用06，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> #现在 我们来看一下 整型的数据
mysql> #tinyint  1字节  -128-127  或者 0-255
mysql> #smallint 2字节  -32768----32767  或者 0----65535
mysql>  #mediumint 3字节  -8488608---8388607 或者 0---16777215
mysql> #int 4字节
mysql> #bigint  8字节
mysql>
mysql> create table ttt(a int(4) zerofill);
ERROR 1050 (42S01): Table 'ttt' already exists
mysql> drop table ttt;
Query OK, 0 rows affected (0.03 sec)

mysql> create table ttt(a int(4) zerofill);
Query OK, 0 rows affected (0.10 sec)

mysql> desc ttt;
+-------+--------------------------+------+-----+---------+-------+
| Field | Type                     | Null | Key | Default | Extra |
+-------+--------------------------+------+-----+---------+-------+
| a     | int(4) unsigned zerofill | YES  |     | NULL    |       |
+-------+--------------------------+------+-----+---------+-------+
1 row in set (0.00 sec)

mysql>  #我们可以看到一个现象 在加了zerofill的属性后  自动设为unsigned
mysql> #mysql数据库支持两种浮点类型 单精度的float类型以及双精度的double precision类型
mysql>  #高精度的类型有decimal  和 numeric
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| Nums           |
| a              |
| employees      |
| new_emp        |
| sales          |
| sessions       |
| t              |
| test01         |
| timetest       |
| ttt            |
| updatetime     |
| yeartest       |
| z              |
+----------------+
13 rows in set (0.00 sec)

mysql> drop table t;
Query OK, 0 rows affected (0.04 sec)

mysql> drop table ttt;
Query OK, 0 rows affected (0.04 sec)

mysql> create table t (a decimal);
Query OK, 0 rows affected (0.11 sec)

mysql> desc table;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'table' at line 1
mysql> desc t;
+-------+---------------+------+-----+---------+-------+
| Field | Type          | Null | Key | Default | Extra |
+-------+---------------+------+-----+---------+-------+
| a     | decimal(10,0) | YES  |     | NULL    |       |
+-------+---------------+------+-----+---------+-------+
1 row in set (0.00 sec)

mysql> create table Nums(
    -> a int unsigned not null primary key
    -> )engine=innodb;
ERROR 1050 (42S01): Table 'Nums' already exists
mysql>
mysql> delimiter //
mysql> create procedure pCreateNum(cnt int unsigned)
    -> begin
    -> declare s int unsigned default 1;
    -> truncate table Nums;
    -> while s<= cnt do
    -> begin
    -> insert into Nums select s;
    -> set s=s+1;
    -> end;
    -> end while;
    -> end;
    -> //
ERROR 1304 (42000): PROCEDURE pCreateNum already exists
mysql> delimiter //
mysql> create procedure pCreateNums(cnt int unsigned)
    -> begin
    -> declare s int unsigned default 1;
    -> truncate table Nums;
    -> while s<= cnt do
    -> begin
    -> insert into Nums select s;
    -> set s=s+1;
    -> end;
    -> end while;
    -> end;
    -> //
Query OK, 0 rows affected (0.00 sec)

mysql> #ok
mysql> #现在我们建立了一个过程函数
mysql> #记得建立的方式 delimiter //   最后//结束
mysql>
mysql> call pCreateNums(1000);
    ->
    -> Ctrl-C -- exit!
Aborted
# the last it has some error

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