About the Not equal number in Oracle:
In Oracle,
<>
!=
~=
^=
is not equal to the meaning of the number. can be used.
But it's weird. Yes, I want to take out a product that price is not 180000: (Price is of type number)
SELECT ID, name from product where Price<> 180000;
When executing this statement, Priceis NULL is not logged. That is, you can't get a commodity that price is null. Must use:
SELECT ID, name from product where price<> 180000 or price is null;Just fine.
The same problem exists with the field of the string.
Remember:Null can only be judged by IS null or is not NULL, and the other operators and null operations are false.
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Test:SELECT * FROM test where name<> ' xn '. Only records with a name that are not empty can be detected. Get rid of name<> ' xn '. There is a problem with this type of wording.
Then use the InStr (name, ' xn ') = 0来 to judge if the name is not empty, the judgment is valid. If name is empty, the judgment goes wrong again. Forced to take InStr (name, ' xx '), ' xn ') = 0来 judgment, because even if the name is empty, and ' xx ' after the connection, it will not be empty.
so the final SQL statement is:
SELECT * FROM Test where InStr (concat (name, ' xx '), ' xn ') = 0To query for records that are not equal to ' xn ' in the Name field.
Or you can use SELECT * FROM Test where NVL (name, ' xx ') <> ' xn 'To query for records that are not equal to ' xn ' in the Name field.
