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.
Then in the second table I have select ..., null as opt from... I know that I could have an empty string with '' as
I read in a book (Thinking in Java by Bruce Eckel, 4th edition, page 47) that null is equal to '\u000'. And then I was wondering what exactly does '\u000' really mean.
Hours 1 1 2 null null null. The result must be: 3. My query is: select count(distinct hour) from hours
What is the difference between … and … and why does the latter not work?
How can I run a MySQL query that selects everything that is not null? It would be something like … Do I just remove the all and go..?
Note: A NULL value is different from a zero value or a field that contains spaces.
Union select null, null, null, null, null, null -- test all nulls --*/ ). A. DECLARE @ColumnDynamicSQL nvarchar(MAX)
Null (or NULL) is a special marker used in Structured Query Language to indicate that a data value does not exist in the database. Introduced by the creator of the relational database model, E. F. Codd...
The IS NOT NULL condition is used in SQL to test for a non-NULL value.