大约有 40,000 项符合查询结果（耗时：0.0542秒） [XML]
Selecting a row of pandas series/dataframe by integer index
...
The primary purpose of the DataFrame indexing operator, [] is to select columns.
When the indexing operator is passed a string or integer, it attempts to find a column with that particular name and return it as a Series.
So, in the question above: df[2] searches for a column name matchin...
How can I select the first day of a month in SQL?
I just need to select the first day of the month of a given datetime variable.
30 Answers
...
Select + copy text in a TextView?
Is there a way to allow the user to select / copy text in a TextView? I need the same functionality of EditText where you can long-press the control and get the popup options of select all / copy, but I need the control to look like a TextView.
...
Pass Array Parameter in SqlCommand
...AddWithValue(parameters[i], items[i]);
}
cmd.CommandText = string.Format("SELECT * from TableA WHERE Age IN ({0})", string.Join(", ", parameters));
cmd.Connection = new SqlConnection(connStr);
UPDATE: Here is an extended and reusable solution that uses Adam's answer along with his suggested edit....
SELECT * FROM X WHERE id IN (…) with Dapper ORM
...
Dapper supports this directly. For example...
string sql = "SELECT * FROM SomeTable WHERE id IN @ids"
var results = conn.Query(sql, new { ids = new[] { 1, 2, 3, 4, 5 }});
share
|
imp...
Swapping column values in MySQL
...rows affected (0.08 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM swaptest;
+------+------+
| X | Y |
+------+------+
| 1 | 2 |
| 3 | 4 |
| -5 | -8 |
| -13 | 27 |
+------+------+
4 rows in set (0.00 sec)
mysql>
Here is the swap being performed
m...
SQLite select where empty?
In SQLite, how can I select records where some_column is empty?
Empty counts as both NULL and "".
4 Answers
...
Iterate through options
I have a <select> element in HTML. This element represents a drop down list. I'm trying to understand how to iterate through the options in the <select> element via JQuery.
...
Selecting only numeric columns from a data frame
...traightforward, and robust to use on database-back-ended tibbles:
dplyr::select_if(x, is.numeric)
share
|
improve this answer
|
follow
|
...
Store select query's output in one array in postgres
...
There are two ways. One is to aggregate:
SELECT array_agg(column_name::TEXT)
FROM information.schema.columns
WHERE table_name = 'aean'
The other is to use an array constructor:
SELECT ARRAY(
SELECT column_name
FROM information.schema.columns
WHERE table_name = ...