原因找到了:就是没太明白为什么?
正确:const sql = `
select username, realname from users where username=${username} and password=${'password'}
`
错误:const sql = `
select username, realname from users where username=${username} and password=${password}
`
错误:const sql = `
select username, realname from users where username=${username} and password='${password}'
`