大约有 40,000 项符合查询结果（耗时：0.0413秒） [XML]
What are DDL and DML?
...als with data
manipulation, and includes most common SQL statements such SELECT,
INSERT, UPDATE, DELETE etc, and it is used to store, modify, retrieve,
delete and update data in database.
SELECT – retrieve data from the a database
INSERT – insert data into a table
UPDATE – up...
How important is the order of columns in indexes?
I've heard that you should put columns that will be the most selective at the beginning of the index declaration. Example:
...
SQL join: selecting the last records in a one-to-many relationship
... want to get a list of all customers along with their last purchase in one SELECT statement. What is the best practice? Any advice on building indexes?
...
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
...
Finding duplicate rows in SQL Server
...abase of organizations, and there are many duplicate rows. I want to run a select statement to grab all of these and the amount of dupes, but also return the ids that are associated with each organization.
...
SQL select only rows with max value on a column [duplicate]
...ce...
All you need is a GROUP BY clause with the MAX aggregate function:
SELECT id, MAX(rev)
FROM YourTable
GROUP BY id
It's never that simple, is it?
I just noticed you need the content column as well.
This is a very common question in SQL: find the whole data for the row with some max value ...
Query grants for a table in postgres
...
I already found it:
SELECT grantee, privilege_type
FROM information_schema.role_table_grants
WHERE table_name='mytable'
share
|
improve this...
JOIN queries vs multiple queries
...han several queries? (You run your main query, and then you run many other SELECTs based on the results from your main query)
...
Correct way to use StringBuilder in SQL
...:
StringBuilder sb = new StringBuilder(some_appropriate_size);
sb.append("select id1, ");
sb.append(id2);
sb.append(" from ");
sb.append(table);
return sb.toString();
Note that I've listed some_appropriate_size in the StringBuilder constructor, so that it starts out with enough capacity for the f...
Fix code indentation in Xcode
...
Before Xcode 9 (for Xcode 9 see default shortcut below)
select text
right-click
there's a "Re-indent selection" item in popup menu
In XCode 4 there is one more step:
select text
right-click
Click on "Structure"
there's a "Re-indent selection" and other options in popup men...