大约有 6,100 项符合查询结果（耗时：0.0305秒） [XML]
What are database normal forms and can you give examples? [closed]
...y normalization, which is a process of organizing columns (attributes) and tables (relations) to reduce data redundancy and improve data integrity. (as written on Wikipedia ).
...
How Do I Choose Between a Hash Table and a Trie (Prefix Tree)?
So if I have to choose between a hash table or a prefix tree what are the discriminating factors that would lead me to choose one over the other. From my own naive point of view it seems as though using a trie has some extra overhead since it isn't stored as an array but that in terms of run time (a...
Make div (height) occupy parent remaining height
...: calc( 100% - 100px ); }
It is pretty widely supported, with the only notable exceptions being <= IE8 or Safari 5 (no support) and IE9 (partial support). Some other issues include using calc in conjunction with transform or box-shadow, so be sure to test in multiple browsers if that is of conc...
PreparedStatement IN clause alternatives?
...lable here.
The suggested options are:
Prepare SELECT my_column FROM my_table WHERE search_column = ?, execute it for each value and UNION the results client-side. Requires only one prepared statement. Slow and painful.
Prepare SELECT my_column FROM my_table WHERE search_column IN (?,?,?) and exe...
SQL JOIN - WHERE clause vs. ON clause
...r join has taken place.
b. ON clause - Before joining. Records (from right table) will be filtered before joining. This may end up as null in the result (since OUTER join).
Example: Consider the below tables:
1. documents:
| id | name |
--------|-------------|
| 1 ...
Insert multiple rows WITHOUT repeating the “INSERT INTO …” part of the statement?
...
INSERT INTO dbo.MyTable (ID, Name)
SELECT 123, 'Timmy'
UNION ALL
SELECT 124, 'Jonny'
UNION ALL
SELECT 125, 'Sally'
For SQL Server 2008, can do it in one VALUES clause exactly as per the statement in your question (you just need to add a comm...
Best way to get identity of inserted row?
...
@@IDENTITY returns the last identity value generated for any table in the current session, across all scopes. You need to be careful here, since it's across scopes. You could get a value from a trigger, instead of your current statement.
SCOPE_IDENTITY() returns the last identity val...
How do I make a column unique and index it in a Ruby on Rails migration?
... What is the best way to do it? Also is there a way to index a column in a table?
8 Answers
...
How to center a checkbox in a table cell?
... contains nothing but a checkbox. It is rather wide because of text in the table header row. How do I center the checkbox (with inline CSS in my HTML? (I know))
...
conditional unique constraint
...unt > 0.
http://msdn.microsoft.com/en-us/library/ms188258.aspx
CREATE TABLE CheckConstraint
(
Id TINYINT,
Name VARCHAR(50),
RecordStatus TINYINT
)
GO
CREATE FUNCTION CheckActiveCount(
@Id INT
) RETURNS INT AS BEGIN
DECLARE @ret INT;
SELECT @ret = COUNT(*) FROM CheckConstraint WHER...