#NodeJS项目#Mysql语句出错

Question

数据库语句：
"select * from user where binary "+" username="+username+" and password="+password+" and type="+type;

目的：查询用户名，密码，type来判断用户是否存在and正确

报错：Error: ER_BAD_FIELD_ERROR: Unknown column 'undefined' in 'where clause'

code: 'ER_BAD_FIELD_ERROR',
errno: 1054,
sqlMessage: "Unknown column 'undefined' in 'where clause'",
sqlState: '42S22',
index: 0,
sql: 'select * from user where binary username=undefined and password=undefined and type=NaN'
}
node:internal/process/promises:246
triggerUncaughtException(err, true /* fromPromise */);
^

[UnhandledPromiseRejection: This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason "登录失败".] {
code: 'ERR_UNHANDLED_REJECTION'

数据库检查了列名对而且没有空格

Answer 1

let sql = "select * from user where binary username="+username+" and password="+password+" and type="+type;
你的sql中where后面为什么要加binary？
改为：let sql = "select * from user where username="+username+" and password="+password+" and type="+type;