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How do I check if a column is empty or null in MySQL?
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This will select all rows where some_col is NULL or '' (empty string)
SELECT * FROM table WHERE some_col IS NULL OR some_col = '';
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Counting the number of option tags in a select tag in jQuery
How do I count the number of <option> s in a <select> DOM element using jQuery?
8 Answers
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Booleans, conditional operators and autoboxing
...nboxing is due to the third operator being of boolean type, like (implicit cast added):
Boolean b = (Boolean) true ? true : false;
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MySQL - Rows to Columns
...ms that I'll use for the rest of this post. This will be the base table:
select * from history;
+--------+----------+-----------+
| hostid | itemname | itemvalue |
+--------+----------+-----------+
| 1 | A | 10 |
| 1 | B | 3 |
| 2 | A | 9...
MySQL Great Circle Distance (Haversine formula)
...ults. To search by kilometers instead of miles, replace 3959 with 6371.
SELECT id, ( 3959 * acos( cos( radians(37) ) * cos( radians( lat ) )
* cos( radians( lng ) - radians(-122) ) + sin( radians(37) ) * sin(radians(lat)) ) ) AS distance
FROM markers
HAVING distance < 25
ORDER BY distance ...
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...
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 ...
WPF ListView turn off selection
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Per Martin Konicek's comment, to fully disable the selection of the items in the simplest manner:
<ListView>
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Setter Property="Focusable" Value="false"/>
&...
How to split a comma-separated value to columns
...TRING(@string, @pos, @len)
INSERT INTO @out_put ([value])
SELECT LTRIM(RTRIM(@value)) AS [column]
SET @pos = CHARINDEX(@delimiter, @string, @pos + @len) + 1
END
RETURN
END
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How do I find numeric columns in Pandas?
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You could use select_dtypes method of DataFrame. It includes two parameters include and exclude. So isNumeric would look like:
numerics = ['int16', 'int32', 'int64', 'float16', 'float32', 'float64']
newdf = df.select_dtypes(include=numer...