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The CAST operator in PostgreSQL

Introduction Cast is a technique in PostgreSQL with which we can convert a value of one datatype into another. We can perform various cast operations in PostgreSQL for converting one datatype to another, such as the String datatype to the Integer datatype (or the Boolean datatype or datetime datatype) and vice versa. This article will […]

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Mathematicians and SQL

Georg Ferdinand Ludwig Philipp Cantor is considered the creator of set theory, and his theories are the basis for the naïve set theory you learned in school. But there are lots of other mathematicians you should know, such as Hilbert, Frege, Russell, Zermelo and Dedekind. They made a lot of contributions, too. Hilbert Hilbert is […]

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DAX financial functions: Depreciation calculations

Business Intelligence Architect, Analysis Services Maestro, and author Bill Pearson continues his series surrounding the DAX financial functions. In this article, he exposes four functions that are popular in the calculation of depreciation and amortization. Those accustomed to these functions within Excel will find the syntax, uses and operation of the functions familiar within the Power BI environment.

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Fun with JSON II

By Steve Jones - SSC Editor

Comments posted to this topic are about the item Fun with JSON II

Changing Data Types

By Steve Jones - SSC Editor

Comments posted to this topic are about the item Changing Data Types

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Question of the Day

Fun with JSON II

I have some data in a table:

CREATE TABLE #test_data
(
    id INT PRIMARY KEY,
    name VARCHAR(100),
    birth_date DATE
);

-- Step 2: Insert rows  
INSERT INTO #test_data
VALUES
(1, 'Olivia', '2025-01-05'),
(2, 'Emma', '2025-03-02'),
(3, 'Liam', '2025-11-15'),
(4, 'Noah', '2025-12-22');
If I run this query, how many rows are returned?
SELECT t1.[key] AS row,
       t2.*
FROM OPENJSON(
     (
         SELECT t.* FROM #test_data AS t FOR JSON PATH
     )
             ) t1
    CROSS APPLY OPENJSON(t1.value) t2;

See possible answers