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What's wrong with nullable columns in composite primary keys?
...ow in a table: when a table has a primary key, you have a guranteed way to select any row from it.
A unique constraint does not necessarily identify every row; it just specifies that if a row has values in its columns, then they must be unique. This is not sufficient to uniquely identify every row...
SQL query return data from multiple tables
...rows affected (0.00 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> select * from colors;
+----+-------+----------+
| id | color | paint |
+----+-------+----------+
| 1 | Red | Metallic |
| 2 | Green | Gloss |
| 3 | Blue | Metallic |
| 4 | White | Gloss |
| 5 | Black | Gloss ...
MySQL SELECT only not null values
Is it possible to do a select statement that takes only NOT NULL values?
9 Answers
9
...
How to convert number to words in java
...o use a built-in function of your DBMS (if available).
For Oracle
SQL> select to_char(to_date(873,'J'), 'JSP') as converted_form from dual;
CONVERTED_FORM
---------------------------
EIGHT HUNDRED SEVENTY-THREE
SQL>
'JSP' means :
J : the Julian format.
SP : spells the word for the number pa...
SQL Logic Operator Precedence: And and Or
...te:
Declare @x tinyInt = 1
Declare @y tinyInt = 0
Declare @z tinyInt = 0
Select Case When @x=1 OR @y=1 And @z=1 Then 'T' Else 'F' End -- outputs T
Select Case When (@x=1 OR @y=1) And @z=1 Then 'T' Else 'F' End -- outputs F
For those who like to consult references (in alphabetic order):
Microso...
What is the difference between “INNER JOIN” and “OUTER JOIN”?
...he intersection of the two tables, i.e. the two rows they have in common.
select * from a INNER JOIN b on a.a = b.b;
select a.*, b.* from a,b where a.a = b.b;
a | b
--+--
3 | 3
4 | 4
Left outer join
A left outer join will give all rows in A, plus any common rows in B.
select * from a LEFT OUT...
T-SQL: Deleting all duplicate rows but keeping one [duplicate]
... I do not care about that. I still need to keep one of these rows however. SELECT DISTINCT won't work because it operates on all columns and I need to suppress duplicates based on the key columns.
...
Best way to do multi-row insert in Oracle?
...acle:
insert into pager (PAG_ID,PAG_PARENT,PAG_NAME,PAG_ACTIVE)
select 8000,0,'Multi 8000',1 from dual
union all select 8001,0,'Multi 8001',1 from dual
The thing to remember here is to use the from dual statement.
(source)
...
Is there a way to call a stored procedure with Dapper?
...:
DECLARE @output int
EXEC <some stored proc> @i = @output OUTPUT
SELECT @output AS output1
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Union Vs Concat in Linq
...ence is not changed.
If you will override Equals and GetHashCode (used to select distinct items), then items will not be compared by reference:
class X
{
public int ID { get; set; }
public override bool Equals(object obj)
{
X x = obj as X;
if (x == null)
re...