大约有 6,887 项符合查询结果（耗时：0.0084秒） [XML]
What's the difference between HEAD, working tree and index, in Git?
Can someone tell me the difference between HEAD, working tree and index, in Git?
5 Answers
...
Create a nonclustered non-unique index within the CREATE TABLE statement with SQL Server
It is possible to create a primary key or unique index within a SQL Server CREATE TABLE statement. Is it possible to create a non-unique index within a CREATE TABLE statement?
...
Is the primary key automatically indexed in MySQL?
Do you need to explicitly create an index, or is it implicit when defining the primary key? Is the answer the same for MyISAM and InnoDB?
...
Making heatmap from pandas DataFrame
...numpy as np
from pandas import DataFrame
import matplotlib.pyplot as plt
index = ['aaa', 'bbb', 'ccc', 'ddd', 'eee']
columns = ['A', 'B', 'C', 'D']
df = DataFrame(abs(np.random.randn(5, 4)), index=index, columns=columns)
plt.pcolor(df)
plt.yticks(np.arange(0.5, len(df.index), 1), df.index)
plt.xt...
How do you check if a certain index exists in a table?
...u can do it using a straight forward select like this:
SELECT *
FROM sys.indexes
WHERE name='YourIndexName' AND object_id = OBJECT_ID('Schema.YourTableName')
share
|
improve this answer
...
Get index of array element faster than O(n)
Given I have a HUGE array, and a value from it. I want to get index of the value in array. Is there any other way, rather then call Array#index to get it? The problem comes from the need of keeping really huge array and calling Array#index enormous amount of times.
...
Does a foreign key automatically create an index?
...I foreign key two tables, that SQL Server will create something akin to an index in the child table. I have a hard time believing this to be true, but can't find much out there related specifically to this.
...
Two single-column indexes vs one two-column index in MySQL?
...
If you have two single column indexes, only one of them will be used in your example.
If you have an index with two columns, the query might be faster (you should measure). A two column index can also be used as a single column index, but only for the co...
What is the difference between join and merge in Pandas?
...ndas as pd
left = pd.DataFrame({'key': ['foo', 'bar'], 'val': [1, 2]}).set_index('key')
right = pd.DataFrame({'key': ['foo', 'bar'], 'val': [4, 5]}).set_index('key')
left.join(right, lsuffix='_l', rsuffix='_r')
val_l val_r
key
foo 1 4
bar 2 5
The same functio...
How do I convert a pandas Series or index to a Numpy array? [duplicate]
Do you know how to get the index or column of a DataFrame as a NumPy array or python list?
8 Answers
...