3 ms·
A more narrow lesson: this is why all SQL statements involving NULL are always false. > in any case, losing power means the transmitter stops transmitting. >
by piaste 4y ago
A more narrow lesson: this is why all SQL statements involving NULL are always false.
> in any case, losing power means the transmitter stops transmitting.
> and here's the fun part: your circuit which controls that inserter is set to insert "if [ICE] < 8000"
> and GETTING NO SIGNAL AT ALL counts the same to it as ICE=0.
> 0 is < 8000.
- deleted 4y ago[deleted]
- sidpatil 4y agoIn industrial automation, one old and popular analog signal scheme is the 4–20 mA current loop [1]. Why 4mA instead of 0mA? Because that way, you know 0mA specifically indicates a fault caused by a failed sensor, break in the line, etc. [1] https://en.wikipedia.org/wiki/Current_loop https://en.wikipedia.org/wiki/Current_loop
- branko_d 4y agoA CHECK constraint treats NULL as true.