在MYSQL创建表时,设置了一个rank字段,作为序号,方便查找,但是不想用它做主键,只是单纯想要它自增。
按照下面语句创建表时始终报错:
CREATE TABLE xyz (
rank INT AUTO_INCREMENT,
tdate VARCHAR(20) PRIMARY KEY,
increase VARCHAR(10),
amplitude VARCHAR(10),
amount INT,
tvalue FLOAT,
turnoverRate FLOAT
);
错误代码: 1075
Incorrect table definition; there can be only one auto column and it must be defined as a key
最后上网查了查,修改为下面语句后成功了:
CREATE TABLE xyz (
rank INT AUTO_INCREMENT,
tdate VARCHAR(20) PRIMARY KEY,
increase VARCHAR(10),
amplitude VARCHAR(10),
amount INT,
tvalue FLOAT,
turnoverRate FLOAT,
KEY(rank)
);
就增加了一行KEY(rank),这个KEY(字段名)是什么意思?