Featured Post

Python map() and lambda() Use Cases and Examples

-
Image
 In Python, map() and lambda functions are often used together for functional programming. Here are some examples to illustrate how they work. Python map and lambda top use cases 1. Using map() with lambda The map() function applies a given function to all items in an iterable (like a list) and returns a map object (which can be converted to a list). Example: Doubling Numbers numbers = [ 1 , 2 , 3 , 4 , 5 ] doubled = list ( map ( lambda x: x * 2 , numbers)) print (doubled) # Output: [2, 4, 6, 8, 10] 2. Using map() to Convert Data Types Example: Converting Strings to Integers string_numbers = [ "1" , "2" , "3" , "4" , "5" ] integers = list ( map ( lambda x: int (x), string_numbers)) print (integers) # Output: [1, 2, 3, 4, 5] 3. Using map() with Multiple Iterables You can also use map() with more than one iterable. The lambda function can take multiple arguments. Example: Adding Two Lists Element-wise list1 = [ 1 , 2 , 3 ]
Post a Comment

How to Resolve ORA-01722 Invalid Number Error in Oracle SQL Developer

-
When working with Oracle SQL Developer, you may come across an error message that reads "ORA-01722: invalid number". This error can be frustrating and difficult to understand, especially if you're new to SQL. In this post, I will explain the cause of this error and provide a solution to resolve it.


Invalid Number Error


Cause of the Error - ORA-01722


Let's consider an example where we have two tables named "my_hr" and "my_dept". The "my_hr" table contains three columns - "name", "pay_id", and "user_id", while the "my_dept" table contains two columns - "name" and "user_id".

CREATE TABLE my_hr (
name CHAR(20),
pay_id NUMBER,
user_id CHAR(6)
);

CREATE TABLE my_dept (
name CHAR(20),
user_id CHAR(6)
);

Now, let's insert some sample data into these tables:

INSERT INTO my_hr VALUES ('Srini', 567, '123456');
INSERT INTO my_dept VALUES ('Srini', '123456');

If we try to execute the following SELECT query to join these two tables using the "name" and "user_id" columns and filter the results based on the "pay_id" column, we will get the "ORA-01722: invalid number" error:

SELECT *
FROM my_hr a, my_dept b
WHERE name = 'Srini'
AND pay_id = '123456' -- This causes the error
AND a.user_id = b.user_id;

The reason for this error is that we are comparing a number column "pay_id" with a string literal value ('123456').

Solution to Resolve the Error:


To fix the error, we need to make sure that we are comparing the "pay_id" column with a number value instead of a string. We can do this by removing the single quotes from the value we are comparing:

SELECT *
FROM my_hr a, my_dept b
WHERE name = 'Srini'
AND pay_id = 123456 -- This is the corrected version
AND a.user_id = b.user_id;

By removing the single quotes from the value of the "pay_id" column, we can compare it with the number column correctly.

Comments

Post a Comment

Thanks for your message. We will get back you.

Popular posts from this blog

How to Fix datetime Import Error in Python Quickly

-
Image
Here's a quick resolution for import datetime Python error . The reason is your .py python script name and datetime  are the same. I'll show you how this error happens and its resolution.   Here's the Resolution for ImportError I've created a script called 'datetime.py.' to check whether the minute value is 'odd' or not. During the import of my python script, I got the import error cannot import name datetime. My Script: datetime.py My script's intention is to find whether the minute value is odd or not. Python Logic from datetime import datetime odds = [ 1 , 3 , 5 , 7 , 9 , 11 , 13 , 15 , 17 , 19 , 21 , 23 , 25 , 27 , 29 , 31 , 33 , 35 , 37 , 39 , 41 , 43 , 45 , 47 , 49 , 51 , 53 , 55 , 57 , 59 ] right_this_minute = datetime.today().minute if right_this_minute in odds: print ( "This minute seems a little odd." ) else : print ( "Not an odd minute." ) ImportError I have imported my datetime.py from Linux. It gives an error
Read more

SQL Query: 3 Methods for Calculating Cumulative SUM

-
Image
SQL provides various constructs for calculating cumulative sums, offering flexibility and efficiency in data analysis. In this article, we explore three distinct SQL queries that facilitate the computation of cumulative sums. Each query leverages different SQL constructs to achieve the desired outcome, catering to diverse analytical needs and preferences. Using Window Functions (e.g., PostgreSQL, SQL Server, Oracle) SELECT id, value, SUM(value) OVER (ORDER BY id) AS cumulative_sum  FROM your_table; This query uses the SUM() window function with the OVER clause to calculate the cumulative sum of the value column ordered by the id column. Using Subqueries (e.g., MySQL, SQLite): SELECT t1.id, t1.value, SUM(t2.value) AS cumulative_sum FROM your_table t1 JOIN your_table t2 ON t1.id >= t2.id GROUP BY t1.id, t1.value ORDER BY t1.id; This query uses a self-join to calculate the cumulative sum. It joins the table with itself, matching rows where the id in the first table is greater than or
Read more

Python placeholder '_' Perfect Way to Use it

-
Image
What is placeholder in Python? The purpose of it is to mask the variable that you don't want to use in a function. In python, y ou can call the underscore ( _ ) operator placeholder. Below, you'll find how to use single and double placeholders in a function. What is placeholder in python The purpose of placeholder in Python is to mask variables that you don't want to use in a function. So that your code will be readable. Moreover, in future, if you want to use those variables you can replace the placeholders with the names you want. In This Page You'll know in three steps how to use placeholder correctly. Creating a function Logic to use single placeholder Logic to use two placeholders 1. Creating a function. def function_that_returns_multiple_values(x):        return x*2, x*3, x+1        for i in range(0,5):             square, cube, added_one = function_that_returns_multiple_values(i)             print(square, cube) Here, in print, it returns two variables. I will s
Read more