why won't this sql query display nothing?

SELECT * FROM开发者_如何学Python date WHERE name = 'etc' AND lastname = 'etc' AND etc='etc'

SQL is declarative, which roughly means that you describe what you want and the database decides on the best way to carry that out. Your query asks the database to find rows where the following is true:

WHERE name = 'etc' AND lastname = 'etc' AND etc='etc'

i.e. where name, lastname and etc in a given row meets your criteria. If you want data where that condition is true, but not necessarily for the same row, then you will want to use OR instead of AND.

maybe there is no row which fits your condition?