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Home Backend Development PHP Tutorial 开发时,如何选取mysql字段长度

开发时,如何选取mysql字段长度

Jun 23, 2016 pm 02:12 PM

如我要存个值为:0123456789,选int型的那么他的"长度/值"该写多少呢?如何计算的 我发现这个长度/值写1,居然也能存进去,或者我要存字符串"你的名字"这4个字,选varchar型的,长度/值又该写多少呢


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只有 varchar、char 类型字段才需要设置宽度,宽度按字符计算
注意:一个汉字是一个字符,但需要设置合适的“整理”

只有 varchar、char 类型字段才需要设置宽度,宽度按字符计算
注意:一个汉字是一个字符,但需要设置合适的“整理”
按照这样说 int 型的 不需要设置 "长度/值"吗(phpmyadmin里),能举例说明吗

好贴,学习了

CREATE TABLE test_str_and_int(
 id int(10) NOT NULL auto_increment,
 str1 VARCHAR(3) NOT NULL,
 str2  VARCHAR(30) NOT NULL,
 test_int_1 TINYINT(1) NOT NULL DEFAULT 1 ,
 test_int_2 SMALLINT(5) NOT NULL  DEFAULT 1,
PRIMARY key(id)
)ENGINE =MYISAM character set utf8;
drop table test_str_and_int
DESC test_str_and_int
#-------------------------------------------------
insert into test_str_and_int (str1,str2,test_int_1,test_int_2) values
('testone','testone',1234567890,1234567890),
('你的名字','你的名字',1234567890,1234567890),
('test你的名字','test你的名字',6789,6789),
('你的名字test','不管插入sql语句多少字符,都会根据数据字段设计的长度进行保留',19860502,19860503)
#---str1--------------------------------------------------
SELECT * FROM test_str_and_int
id str1   str2       int_1 int_2
1  tes   testone    127 32767
2  你的名 你的名字 127 32767
3  tes   test你的名字 127 6789
4  你的名 不管插入sql语句多少字符,都会根据数据字段设计的长度进行保 127 32767

#---总结--------str1 ,str2 是字符串型的-,长度分别设计为varchar(3),varcvhar(30)插入数据库后,分别保留3个字符串长度和30个字符串长度
#不管插入sql语句多少字符,都会根据数据字段设计的长度进行保留-,可以根据需要设计长度,一般的情况下字符串长度为20或者32基本上可以满足
#-同理int类型也基本如此

char和varchar的长度是一个汉字两个字符,你最多放4个字的话长度就设置为8,然后他肯定放不进去5个字!至于int长度为1为什么也能存进去0123456789  我认为是这串数字你以0打头数据库自动判断为0了,你把长度设置成1  然后存个123456789试试

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