大约有 46,000 项符合查询结果（耗时：0.0453秒） [XML]
How do I (or can I) SELECT DISTINCT on multiple columns?
...
SELECT DISTINCT a,b,c FROM t
is roughly equivalent to:
SELECT a,b,c FROM t GROUP BY a,b,c
It's a good idea to get used to the GROUP BY syntax, as it's more powerful.
For your query, I'd do it like this:
UPDATE sale...
How to select bottom most rows?
I can do SELECT TOP (200) ... but why not BOTTOM (200)?
14 Answers
14
...
Can we pass parameters to a view in SQL?
..., like:
CREATE FUNCTION v_emp (@pintEno INT)
RETURNS TABLE
AS
RETURN
SELECT * FROM emp WHERE emp_id=@pintEno;
This allows you to use it as a normal view, with:
SELECT * FROM v_emp(10)
share
|
...
What is the difference between HAVING and WHERE in SQL?
What is the difference between HAVING and WHERE in an SQL SELECT statement?
20 Answers
...
Get table names using SELECT statement in MySQL
...
To get the name of all tables use:
SELECT table_name FROM information_schema.tables;
To get the name of the tables from a specific database use:
SELECT table_name FROM information_schema.tables
WHERE table_schema = 'your_database_name';
Now, to answer the...
Create table (structure) from existing table
...
Try:
Select * Into <DestinationTableName> From <SourceTableName> Where 1 = 2
Note that this will not copy indexes, keys, etc.
If you want to copy the entire structure, you need to generate a Create Script of the tab...
'IF' in 'SELECT' statement - choose output value based on column values
...
SELECT id,
IF(type = 'P', amount, amount * -1) as amount
FROM report
See http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html.
Additionally, you could handle when the condition is null. In the case of...
Join vs. sub-query
...
@JinghuiNiu Customers who bought expensive items: select custid from cust join bought using (custid) where price > 500. If a customer bought multiple expensive items, you'll get double-ups. To fix this, select custid from cust where exists (select * from bought where cust...
Prevent text selection after double click
...lick event on a span in my web app. A side-effect is that the double click selects text on the page. How can I prevent this selection from happening?
...
How to concatenate columns in a Postgres SELECT?
... an explicit coercion to text [...]
Bold emphasis mine. The 2nd example (select a||', '||b from foo) works for any data types since the untyped string literal ', ' defaults to type text making the whole expression valid in any case.
For non-string data types, you can "fix" the 1st statement by c...