If I have the table … This will display Firstname-Middlename-Surname e.g. … The second one (Jane’s) displays correct, however since John doesn’t have a middlename, I want it to ignore the second dash.
SELECT COUNT(*), 'null_tally' AS narrative FROM us WHERE a IS NULL UNION SELECT COUNT(*), 'not_null_tally' AS narrative FROM
select a,b,null,null from table1 union select null,null,c,d from table2 union select null,null,null,null,e,f from table3.
I want to select a concatenation of a couple of fields, but with a separator between them. The separator should only be there if both operands are not null.
mysql> SELECT NULL, 1+NULL, CONCAT('Invisible',NULL); To search for column values that are NULL, you cannot use an expr = NULL test. The following statement returns no rows, because expr = NULL is never true for any expression: Press CTRL+C to copy. mysql> SELECT * FROM my_table...
What is the difference between … and … and why does the latter not work?
SELECT CONCAT("SQL ", "Tutorial ", "is ", "fun!") AS ConcatenatedString; Try it Yourself ». Definition and Usage. The CONCAT() function adds two or more expressions together. Note: Also look at the CONCAT_WS() function. Syntax.
The Background I was trying to solve the fourth realistic mission in hackthissite.org, and couldn't figure out exactly what SQL I should inject into the URL to retrieve the list of emails.
Существуют специальные операторы IS NULL и IS NOT NULL, которы�� позволяют производить сравнения с NULLами.
The IS NULL operator is used to test for empty values (NULL values). The following SQL lists all customers with a NULL value in the "Address" field: Example. SELECT CustomerName, ContactName, Address FROM Customers WHERE Address IS NULL