大约有 47,000 项符合查询结果（耗时：0.0332秒） [XML]
What is this operator in MySQL?
...d <> both give UNKNOWN with NULL on either side of the expression.)
SELECT *
FROM table
WHERE YourColumn IS NOT NULL;
can also negate the null safe equality operator but this is not standard SQL.
SELECT *
FROM table
WHERE NOT (YourColumn <=> NULL);
...
SQL Server dynamic PIVOT query?
... @cols AS NVARCHAR(MAX),
@query AS NVARCHAR(MAX);
SET @cols = STUFF((SELECT distinct ',' + QUOTENAME(c.category)
FROM temp c
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set @query = 'SELECT date, ' + @cols + ' from
(...
XPath: select text node
... XML:
<node>Text1<subnode/>text2</node>
How do I select either the first or
the second text node via XPath?
Use:
/node/text()
This selects all text-node children of the top element (named "node") of the XML document.
/node/text()[1]
This selects the first text-nod...
INSERT with SELECT
I have a query that inserts using a select:
8 Answers
8
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Finding duplicate values in a SQL table
...
SELECT
name, email, COUNT(*)
FROM
users
GROUP BY
name, email
HAVING
COUNT(*) > 1
Simply group on both of the columns.
Note: the older ANSI standard is to have all non-aggregated columns in the GROUP BY ...
How can I remove the gloss on a select element in Safari on Mac?
On Macs and iOS devices, in Safari, a <select> element with a background color generates a gloss over itself. This does not seem to happen in other operating systems.
...
Android ViewPager with bottom dots
...droid:layout_height="wrap_content"
app:tabBackground="@drawable/tab_selector"
app:tabGravity="center"
app:tabIndicatorHeight="0dp"/>
</RelativeLayout>
Hook up your UI elements inactivity or fragment as follows:
Java Code:
mImageViewPager = (ViewPager) findViewById(R.id...
Check if a Postgres JSON array contains a string
...
As of PostgreSQL 9.4, you can use the ? operator:
select info->>'name' from rabbits where (info->'food')::jsonb ? 'carrots';
You can even index the ? query on the "food" key if you switch to the jsonb type instead:
alter table rabbits alter info type jsonb using ...
get list of pandas dataframe columns based on data type
...
If you are just selecting columns by data type, then this answer is obsolete. Use select_dtypes instead
– Ted Petrou
Nov 3 '17 at 16:58
...
Dynamic SELECT TOP @var In SQL Server
...
SELECT TOP (@count) * FROM SomeTable
This will only work with SQL 2005+
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