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SQL Query: 3 Methods for Calculating Cumulative SUM

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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

The Exclusive Way to Declare Variables in Oracle Procedure

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There are four data types in PLSQL. Those are Numeric, Char, Boolean, and Date/Time. Each data type and its features are demonstrated. And explained how to declare variables in PLSQL procedure. Data types Here are the four popular data types in PLSQL. 1. Numeric DEC, DECIMAL, and NUMERIC are used to declare fixed-point numbers with a precision of a maximum of 38 decimal digits. INTEGER, INT , and SMALLINT declare integers with a maximum precision of 38 digits. 2. Char Char and Varchar data types support storing data of 1 t0 2000 bytes. The VARCHAR2 supports 1 to 4000 bytes of data. The VARCHAR and VARCHAR2 release the unused space in memory,  3. Date/Time The range for the Date is from 01-Jan-4712 BC to 31-DEC-9999. It stores the data in date format DD-MON-YYYY. The value is written in single quotes. 4. Boolean BOOLEAN datatype stores logical values and can be either TRUE or FALSE. Declare variables The Declare block in PL/SQL is reserved for variable declaration. The code between beg

SQL PLSQL Top Reserved Keywords

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To become perfect in PL/SQL is an art. Knowing of top reserved words helps you to be a master in SQL. Before you start knowing reserved words, wait one moment. The reserved words are similar to the words that you use in normal SQL. SQL, PLSQL Reserved Words PL/SQL Reserved Words A Video on Basic PL/SQL Basic PL/SQL Video Lesson for all professionals. Related Posts 32 Complex SQL Queries popular e-book Introduction to SQL and PLSQL by Ruchin Jain

PL SQL: How to Fix Errors

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PL/SQL is procedural language, and the PL/SQL procedures you can call from any high-level language. This is depending on your project requirement. PL SQL  How to prevent some common errors or exceptions while writing PL/SQL procedures in your project. The number one and primary one is assigning variables non-numeric to numeric. This is one kind of area where you need to look in while writing PL/SQL procedure. PL/SQL is nothing but an invitation for trouble. They are all centered on data types and implicit conversion. What's implicit conversion? Let's say you have number held in a varchar2 data type variable, v_value. You try assigning n_value, a number data type variable, that value with the following line of code:n_value := v_value; That should work, right? Yes, it should, but when it doesn't, because you don't actually have a numeric literal stored in variable v_value, the implicit data type conversion will raise an "unexpected" exception in

PL/SQL Sample code and error handling mechanism

SAMPLE PL/SQL CREATE TABLE dummy ( dummy_value VARCHAR2(1)); DECLARE -- Define local variable. my_string VARCHAR2(1) := ' '; my_number NUMBER; BEGIN -- Select a white space into a local variable. SELECT ' ' INTO my_string FROM dummy; -- Attempt to assign a single white space to a number. my_number := TO_NUMBER(my_string); EXCEPTION WHEN no_data_found THEN dbms_output.put_line('SELECT-INTO'||CHR(10)||SQLERRM); END; / Output and Error: The program returns the following output, which illustrates formatting user- defined exceptions.  The CHR(10) inserts a line return and provides a clean break between the program's SQLCODE and SQLERRM messages: RAISE my_error SQLCODE [1]  SQLERRM [User-Defined Exception]