--find SQL login with blank passwords
select name,type_desc,create_date from sys.sql_logins where pwdcompare('', password_hash) = 1

--find SQL login with password same as name
select name,type_desc,create_date from sys.sql_logins where pwdcompare(name, password_hash) = 1

--比对sa的密码是否为123abc
SELECT TOP 50 * 
FROM sys.sql_logins sl
WHERE name = 'sa' AND pwdcompare('123abc', password_hash) = 1