In SQLAlchemy, you can select only one column from a table by using the select() function along with the column() function to specify the column you want. Here's how you can do it:
from sqlalchemy import create_engine, select, column
from sqlalchemy.orm import sessionmaker
from your_module import YourTable # Replace with the actual module and table name
# Create a SQLAlchemy engine
engine = create_engine("your_database_url")
# Create a session
Session = sessionmaker(bind=engine)
session = Session()
# Select only one column using SQLAlchemy
stmt = select(column("column_name")) # Replace with the actual column name
result = session.execute(stmt).fetchall()
# Print the result
for row in result:
print(row[0]) # Column value
In the above code:
"your_database_url" with the actual URL to your database.YourTable with the actual table class name from your module."column_name" with the actual name of the column you want to select.The select() function constructs a SQL SELECT statement, and the column() function allows you to specify the specific column you want to retrieve. The execute() function is used to execute the constructed statement, and fetchall() retrieves all the results.
Note that using column() to select only one column is useful when you don't need the entire row object and want to retrieve just the values of that specific column.
To specify the version of your Python project in only one place when using pyproject.toml, you can use the poetry dependency management tool. Poetry allows you to manage your project dependencies and metadata, including the version, in a single file (pyproject.toml), making it easy to keep everything in sync.
Here's how you can specify the version in one place using Poetry:
pip install poetry
poetry init
This command will prompt you to fill in various project details, including the project name, version, author, and description. At this stage, you can specify the initial version of your project.
pyproject.toml:
After running poetry init, your project will have a pyproject.toml file in the project's root directory. Open this file using a text editor, and you'll see a section like this:[tool.poetry] name = "your-project-name" version = "0.1.0" description = "Your project description" authors = ["Your Name <[email protected]>"]
You can set the version directly in this pyproject.toml file under the [tool.poetry] section. Update the version field to the desired version number, like this:
[tool.poetry] name = "your-project-name" version = "1.2.3" # Update to your desired version number description = "Your project description" authors = ["Your Name <[email protected]>"]
poetry.version attribute. For example:import poetry print(poetry.version.__version__) # This will print the version from pyproject.toml
By using Poetry to manage your project's dependencies and metadata, you only need to specify the version in the pyproject.toml file. This makes it easy to keep track of the version throughout your project, and you can easily update it in one place whenever necessary.
You can use the openpyxl library in Python to read only one column from an Excel file. Here's a step-by-step guide on how to do this:
openpyxl library if you haven't already:pip install openpyxl
import openpyxl
openpyxl.load_workbook():file_path = "path/to/your/excel/file.xlsx" workbook = openpyxl.load_workbook(file_path)
worksheet = workbook["Sheet1"] # Replace "Sheet1" with the actual sheet name
column_index = 1 # Replace with the index of the column you want to read (1-based)
column_values = []
for row in worksheet.iter_rows(min_row=2, max_row=worksheet.max_row, min_col=column_index, max_col=column_index):
cell_value = row[0].value
column_values.append(cell_value)
In the above code, min_row=2 is used to skip the header row. Adjust it according to your Excel file structure.
Now column_values contains all the values from the specified column. You can process these values as needed.
Don't forget to close the workbook when you're done:
workbook.close()
Putting it all together:
import openpyxl
file_path = "path/to/your/excel/file.xlsx"
workbook = openpyxl.load_workbook(file_path)
worksheet = workbook["Sheet1"]
column_index = 1
column_values = []
for row in worksheet.iter_rows(min_row=2, max_row=worksheet.max_row, min_col=column_index, max_col=column_index):
cell_value = row[0].value
column_values.append(cell_value)
workbook.close()
print(column_values)
Remember to replace "Sheet1" with the actual name of the worksheet you want to read from, and adjust the column_index to match the column you're interested in.